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Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node

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  Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Mark Rutland <mark.rutland@arm.com> - 2015-08-21 20:50 +0200
    Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leo Yan <leo.yan@linaro.org> - 2015-08-22 15:40 +0200
      Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leo Yan <leo.yan@linaro.org> - 2015-08-24 05:30 +0200
    Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leo Yan <leo.yan@linaro.org> - 2015-08-24 11:20 +0200
      Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Mark Rutland <mark.rutland@arm.com> - 2015-08-24 12:00 +0200
        Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Haojian Zhuang <haojian.zhuang@linaro.org> - 2015-08-24 12:30 +0200
          Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leif Lindholm <leif.lindholm@linaro.org> - 2015-08-24 13:50 +0200
            Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Haojian Zhuang <haojian.zhuang@linaro.org> - 2015-08-25 10:20 +0200
              Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leif Lindholm <leif.lindholm@linaro.org> - 2015-08-25 11:50 +0200
                Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Haojian Zhuang <haojian.zhuang@linaro.org> - 2015-08-25 12:20 +0200
                  Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leif Lindholm <leif.lindholm@linaro.org> - 2015-08-25 12:50 +0200
                  Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Mark Rutland <mark.rutland@arm.com> - 2015-08-25 12:50 +0200
                    Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Haojian Zhuang <haojian.zhuang@linaro.org> - 2015-08-25 15:50 +0200
                      Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leif Lindholm <leif.lindholm@linaro.org> - 2015-08-25 16:30 +0200
                        Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-08-25 17:00 +0200
                          Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leif Lindholm <leif.lindholm@linaro.org> - 2015-08-25 17:40 +0200
                            Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-08-25 17:50 +0200
                            Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Haojian Zhuang <haojian.zhuang@linaro.org> - 2015-08-26 04:50 +0200
                      Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leo Yan <leo.yan@linaro.org> - 2015-08-25 18:10 +0200
                        Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Haojian Zhuang <haojian.zhuang@linaro.org> - 2015-08-26 03:30 +0200
                          Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leo Yan <leo.yan@linaro.org> - 2015-08-26 09:10 +0200
                            Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Mark Rutland <mark.rutland@arm.com> - 2015-08-27 18:40 +0200
                              Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Leo Yan <leo.yan@linaro.org> - 2015-08-28 08:40 +0200
                          Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Daniel Thompson <daniel.thompson@linaro.org> - 2015-08-27 18:00 +0200
                          Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Mark Rutland <mark.rutland@arm.com> - 2015-08-27 18:50 +0200
          Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Mark Rutland <mark.rutland@arm.com> - 2015-08-24 14:50 +0200
            Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Haojian Zhuang <haojian.zhuang@linaro.org> - 2015-08-25 10:20 +0200
              Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node Mark Rutland <mark.rutland@arm.com> - 2015-08-25 13:10 +0200

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#1211298 — Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node

On Wed, Aug 19, 2015 at 10:37:35AM +0100, Leo Yan wrote:
> On Hi6220, below memory regions in DDR have specific purpose:
> 
>   0x05e0,0000 - 0x05ef,ffff: For MCU firmware using at runtime;
>   0x0740,f000 - 0x0740,ffff: For MCU firmware's section;
>   0x06df,f000 - 0x06df,ffff: For mailbox message data.
> 
> This patch reserves these memory regions and add device node for
> mailbox in dts.
> 
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>  arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 20 +++++++++++++++++---
>  arch/arm64/boot/dts/hisilicon/hi6220.dtsi      |  8 ++++++++
>  2 files changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> index e36a539..d5470d3 100644
> --- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> +++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> @@ -7,9 +7,6 @@
>  
>  /dts-v1/;
>  
> -/*Reserved 1MB memory for MCU*/
> -/memreserve/ 0x05e00000 0x00100000;
> -
>  #include "hi6220.dtsi"
>  
>  / {
> @@ -28,4 +25,21 @@
>  		device_type = "memory";
>  		reg = <0x0 0x0 0x0 0x40000000>;
>  	};
> +
> +	reserved-memory {
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +
> +		mcu-buf@05e00000 {
> +			no-map;
> +			reg = <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
> +			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
> +		};
> +
> +		mbox-buf@06dff000 {
> +			no-map;
> +			reg = <0x0 0x06dff000 0x0 0x00001000>;	/* Mailbox message buf */
> +		};
> +	};

As far as I can see, it would be simpler to simply carve these out of the
memory node.

I don't see why you need reserved-memory here, given you're not referring to
these regions by phandle anyway.

Thanks,
Mark.


>  };
> diff --git a/arch/arm64/boot/dts/hisilicon/hi6220.dtsi b/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> index 3f03380..9ff25bc 100644
> --- a/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> +++ b/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> @@ -167,5 +167,13 @@
>  			clocks = <&ao_ctrl 36>, <&ao_ctrl 36>;
>  			clock-names = "uartclk", "apb_pclk";
>  		};
> +
> +		mailbox: mailbox@f7510000 {
> +			#mbox-cells = <1>;
> +			compatible = "hisilicon,hi6220-mbox";
> +			reg = <0x0 0xf7510000 0x0 0x1000>, /* IPC_S */
> +			      <0x0 0x06dff800 0x0 0x0800>; /* Mailbox buffer */
> +			interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
> +		};
>  	};
>  };
> -- 
> 1.9.1
> 
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#1211458

Hi Mark,

On Fri, Aug 21, 2015 at 07:40:59PM +0100, Mark Rutland wrote:
> On Wed, Aug 19, 2015 at 10:37:35AM +0100, Leo Yan wrote:
> > On Hi6220, below memory regions in DDR have specific purpose:
> > 
> >   0x05e0,0000 - 0x05ef,ffff: For MCU firmware using at runtime;
> >   0x0740,f000 - 0x0740,ffff: For MCU firmware's section;
> >   0x06df,f000 - 0x06df,ffff: For mailbox message data.
> > 
> > This patch reserves these memory regions and add device node for
> > mailbox in dts.
> > 
> > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > ---
> >  arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 20 +++++++++++++++++---
> >  arch/arm64/boot/dts/hisilicon/hi6220.dtsi      |  8 ++++++++
> >  2 files changed, 25 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > index e36a539..d5470d3 100644
> > --- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > +++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > @@ -7,9 +7,6 @@
> >  
> >  /dts-v1/;
> >  
> > -/*Reserved 1MB memory for MCU*/
> > -/memreserve/ 0x05e00000 0x00100000;
> > -
> >  #include "hi6220.dtsi"
> >  
> >  / {
> > @@ -28,4 +25,21 @@
> >  		device_type = "memory";
> >  		reg = <0x0 0x0 0x0 0x40000000>;
> >  	};
> > +
> > +	reserved-memory {
> > +		#address-cells = <2>;
> > +		#size-cells = <2>;
> > +		ranges;
> > +
> > +		mcu-buf@05e00000 {
> > +			no-map;
> > +			reg = <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
> > +			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
> > +		};
> > +
> > +		mbox-buf@06dff000 {
> > +			no-map;
> > +			reg = <0x0 0x06dff000 0x0 0x00001000>;	/* Mailbox message buf */
> > +		};
> > +	};
> 
> As far as I can see, it would be simpler to simply carve these out of the
> memory node.

Will modify for MCU firmware buffer and section.

> I don't see why you need reserved-memory here, given you're not referring to
> these regions by phandle anyway.

mbox-buf is used by below mailbox's node, but the start address has
been truncated with 4KB alignment; so should keep it, right?

Thanks,
Leo Yan

> >  };
> > diff --git a/arch/arm64/boot/dts/hisilicon/hi6220.dtsi b/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> > index 3f03380..9ff25bc 100644
> > --- a/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> > +++ b/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> > @@ -167,5 +167,13 @@
> >  			clocks = <&ao_ctrl 36>, <&ao_ctrl 36>;
> >  			clock-names = "uartclk", "apb_pclk";
> >  		};
> > +
> > +		mailbox: mailbox@f7510000 {
> > +			#mbox-cells = <1>;
> > +			compatible = "hisilicon,hi6220-mbox";
> > +			reg = <0x0 0xf7510000 0x0 0x1000>, /* IPC_S */
> > +			      <0x0 0x06dff800 0x0 0x0800>; /* Mailbox buffer */
> > +			interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
> > +		};
> >  	};
> >  };
> > -- 
> > 1.9.1
> > 
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#1211745

Hi Mark,

On Sat, Aug 22, 2015 at 09:30:50PM +0800, Leo Yan wrote:
> On Fri, Aug 21, 2015 at 07:40:59PM +0100, Mark Rutland wrote:
> > On Wed, Aug 19, 2015 at 10:37:35AM +0100, Leo Yan wrote:
> > > On Hi6220, below memory regions in DDR have specific purpose:
> > > 
> > >   0x05e0,0000 - 0x05ef,ffff: For MCU firmware using at runtime;
> > >   0x0740,f000 - 0x0740,ffff: For MCU firmware's section;
> > >   0x06df,f000 - 0x06df,ffff: For mailbox message data.
> > > 
> > > This patch reserves these memory regions and add device node for
> > > mailbox in dts.
> > > 
> > > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > > ---
> > >  arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 20 +++++++++++++++++---
> > >  arch/arm64/boot/dts/hisilicon/hi6220.dtsi      |  8 ++++++++
> > >  2 files changed, 25 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > index e36a539..d5470d3 100644
> > > --- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > +++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > @@ -7,9 +7,6 @@
> > >  
> > >  /dts-v1/;
> > >  
> > > -/*Reserved 1MB memory for MCU*/
> > > -/memreserve/ 0x05e00000 0x00100000;
> > > -
> > >  #include "hi6220.dtsi"
> > >  
> > >  / {
> > > @@ -28,4 +25,21 @@
> > >  		device_type = "memory";
> > >  		reg = <0x0 0x0 0x0 0x40000000>;
> > >  	};
> > > +
> > > +	reserved-memory {
> > > +		#address-cells = <2>;
> > > +		#size-cells = <2>;
> > > +		ranges;
> > > +
> > > +		mcu-buf@05e00000 {
> > > +			no-map;
> > > +			reg = <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
> > > +			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
> > > +		};
> > > +
> > > +		mbox-buf@06dff000 {
> > > +			no-map;
> > > +			reg = <0x0 0x06dff000 0x0 0x00001000>;	/* Mailbox message buf */
> > > +		};
> > > +	};
> > 
> > As far as I can see, it would be simpler to simply carve these out of the
> > memory node.
> 
> Will modify for MCU firmware buffer and section.
> 
> > I don't see why you need reserved-memory here, given you're not referring to
> > these regions by phandle anyway.
> 
> mbox-buf is used by below mailbox's node, but the start address has
> been truncated with 4KB alignment; so should keep it, right?

I think i got your point, all these nodes can be removed and just use
memory node to carve them out; but currently i saw the memory node
cannot be passed correctly from UEFI to kernel, we will check for
this. So will follow your suggestion if without any unknown reason.

Thanks,
Leo Yan

> > >  };
> > > diff --git a/arch/arm64/boot/dts/hisilicon/hi6220.dtsi b/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> > > index 3f03380..9ff25bc 100644
> > > --- a/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> > > +++ b/arch/arm64/boot/dts/hisilicon/hi6220.dtsi
> > > @@ -167,5 +167,13 @@
> > >  			clocks = <&ao_ctrl 36>, <&ao_ctrl 36>;
> > >  			clock-names = "uartclk", "apb_pclk";
> > >  		};
> > > +
> > > +		mailbox: mailbox@f7510000 {
> > > +			#mbox-cells = <1>;
> > > +			compatible = "hisilicon,hi6220-mbox";
> > > +			reg = <0x0 0xf7510000 0x0 0x1000>, /* IPC_S */
> > > +			      <0x0 0x06dff800 0x0 0x0800>; /* Mailbox buffer */
> > > +			interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
> > > +		};
> > >  	};
> > >  };
> > > -- 
> > > 1.9.1
> > > 
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#1211961

Hi Mark,

On Fri, Aug 21, 2015 at 07:40:59PM +0100, Mark Rutland wrote:
> On Wed, Aug 19, 2015 at 10:37:35AM +0100, Leo Yan wrote:
> > On Hi6220, below memory regions in DDR have specific purpose:
> > 
> >   0x05e0,0000 - 0x05ef,ffff: For MCU firmware using at runtime;
> >   0x0740,f000 - 0x0740,ffff: For MCU firmware's section;
> >   0x06df,f000 - 0x06df,ffff: For mailbox message data.
> > 
> > This patch reserves these memory regions and add device node for
> > mailbox in dts.
> > 
> > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > ---
> >  arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 20 +++++++++++++++++---
> >  arch/arm64/boot/dts/hisilicon/hi6220.dtsi      |  8 ++++++++
> >  2 files changed, 25 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > index e36a539..d5470d3 100644
> > --- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > +++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > @@ -7,9 +7,6 @@
> >  
> >  /dts-v1/;
> >  
> > -/*Reserved 1MB memory for MCU*/
> > -/memreserve/ 0x05e00000 0x00100000;
> > -
> >  #include "hi6220.dtsi"
> >  
> >  / {
> > @@ -28,4 +25,21 @@
> >  		device_type = "memory";
> >  		reg = <0x0 0x0 0x0 0x40000000>;
> >  	};
> > +
> > +	reserved-memory {
> > +		#address-cells = <2>;
> > +		#size-cells = <2>;
> > +		ranges;
> > +
> > +		mcu-buf@05e00000 {
> > +			no-map;
> > +			reg = <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
> > +			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
> > +		};
> > +
> > +		mbox-buf@06dff000 {
> > +			no-map;
> > +			reg = <0x0 0x06dff000 0x0 0x00001000>;	/* Mailbox message buf */
> > +		};
> > +	};
> 
> As far as I can see, it would be simpler to simply carve these out of the
> memory node.
> 
> I don't see why you need reserved-memory here, given you're not referring to
> these regions by phandle anyway.

- Now we have enabled EFI_STUB, so the memory node will be removed in
  kernel:
    efi_entry()
      \-> allocate_new_fdt_and_exit_boot()
            \-> update_fdt();

  Finally in kernel it cannot use memory node to carve out reseved
  memory regions.

- On the other hand, DTS's the memory node is to "describes the
  physical memory layout for the system"; so it's better to use it only
  to describe the hardware info for memory. We can use reserved-memory
  to help manage the memory regions which are reserved from software
  perspective.

According to upper info, we still need to use reserved-memory node to
depict the reserved memory regions. i have no knowledge about EFI_STUB,
so please confirm or correct as needed.

Thanks,
Leo Yan
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#1212049

On Mon, Aug 24, 2015 at 10:18:45AM +0100, Leo Yan wrote:
> Hi Mark,
> 
> On Fri, Aug 21, 2015 at 07:40:59PM +0100, Mark Rutland wrote:
> > On Wed, Aug 19, 2015 at 10:37:35AM +0100, Leo Yan wrote:
> > > On Hi6220, below memory regions in DDR have specific purpose:
> > > 
> > >   0x05e0,0000 - 0x05ef,ffff: For MCU firmware using at runtime;
> > >   0x0740,f000 - 0x0740,ffff: For MCU firmware's section;
> > >   0x06df,f000 - 0x06df,ffff: For mailbox message data.
> > > 
> > > This patch reserves these memory regions and add device node for
> > > mailbox in dts.
> > > 
> > > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > > ---
> > >  arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 20 +++++++++++++++++---
> > >  arch/arm64/boot/dts/hisilicon/hi6220.dtsi      |  8 ++++++++
> > >  2 files changed, 25 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > index e36a539..d5470d3 100644
> > > --- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > +++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > @@ -7,9 +7,6 @@
> > >  
> > >  /dts-v1/;
> > >  
> > > -/*Reserved 1MB memory for MCU*/
> > > -/memreserve/ 0x05e00000 0x00100000;
> > > -
> > >  #include "hi6220.dtsi"
> > >  
> > >  / {
> > > @@ -28,4 +25,21 @@
> > >  		device_type = "memory";
> > >  		reg = <0x0 0x0 0x0 0x40000000>;
> > >  	};
> > > +
> > > +	reserved-memory {
> > > +		#address-cells = <2>;
> > > +		#size-cells = <2>;
> > > +		ranges;
> > > +
> > > +		mcu-buf@05e00000 {
> > > +			no-map;
> > > +			reg = <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
> > > +			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
> > > +		};
> > > +
> > > +		mbox-buf@06dff000 {
> > > +			no-map;
> > > +			reg = <0x0 0x06dff000 0x0 0x00001000>;	/* Mailbox message buf */
> > > +		};
> > > +	};
> > 
> > As far as I can see, it would be simpler to simply carve these out of the
> > memory node.
> > 
> > I don't see why you need reserved-memory here, given you're not referring to
> > these regions by phandle anyway.
> 
> - Now we have enabled EFI_STUB, so the memory node will be removed in
>   kernel:
>     efi_entry()
>       \-> allocate_new_fdt_and_exit_boot()
>             \-> update_fdt();
> 
>   Finally in kernel it cannot use memory node to carve out reseved
>   memory regions.
> 
> - On the other hand, DTS's the memory node is to "describes the
>   physical memory layout for the system"; so it's better to use it only
>   to describe the hardware info for memory. We can use reserved-memory
>   to help manage the memory regions which are reserved from software
>   perspective.

The fact that you have no-map means that the memory should not be
described to the kernel as mappable in the first place. It's wrong to
place such memory in the memory node, even if listed in reserved-memory.

If your EFI memory map describes the memory as mappable, it is wrong.

> According to upper info, we still need to use reserved-memory node to
> depict the reserved memory regions. i have no knowledge about EFI_STUB,
> so please confirm or correct as needed.

If the memory shouldn't be mapped, it should neither be in the memory
node nor EFI memory map (with attributes allowing it to be mapped) to
begin with.

As far as I can see you do not need to use reserved-memory.

Thanks,
Mark.
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#1212065

On Mon, 2015-08-24 at 10:51 +0100, Mark Rutland wrote:
> On Mon, Aug 24, 2015 at 10:18:45AM +0100, Leo Yan wrote:
> > Hi Mark,
> > 
> > On Fri, Aug 21, 2015 at 07:40:59PM +0100, Mark Rutland wrote:
> > > On Wed, Aug 19, 2015 at 10:37:35AM +0100, Leo Yan wrote:
> > > > On Hi6220, below memory regions in DDR have specific purpose:
> > > > 
> > > >   0x05e0,0000 - 0x05ef,ffff: For MCU firmware using at runtime;
> > > >   0x0740,f000 - 0x0740,ffff: For MCU firmware's section;
> > > >   0x06df,f000 - 0x06df,ffff: For mailbox message data.
> > > > 
> > > > This patch reserves these memory regions and add device node for
> > > > mailbox in dts.
> > > > 
> > > > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > > > ---
> > > >  arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 20 +++++++++++++++++---
> > > >  arch/arm64/boot/dts/hisilicon/hi6220.dtsi      |  8 ++++++++
> > > >  2 files changed, 25 insertions(+), 3 deletions(-)
> > > > 
> > > > diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > > index e36a539..d5470d3 100644
> > > > --- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > > +++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
> > > > @@ -7,9 +7,6 @@
> > > >  
> > > >  /dts-v1/;
> > > >  
> > > > -/*Reserved 1MB memory for MCU*/
> > > > -/memreserve/ 0x05e00000 0x00100000;
> > > > -
> > > >  #include "hi6220.dtsi"
> > > >  
> > > >  / {
> > > > @@ -28,4 +25,21 @@
> > > >  		device_type = "memory";
> > > >  		reg = <0x0 0x0 0x0 0x40000000>;
> > > >  	};
> > > > +
> > > > +	reserved-memory {
> > > > +		#address-cells = <2>;
> > > > +		#size-cells = <2>;
> > > > +		ranges;
> > > > +
> > > > +		mcu-buf@05e00000 {
> > > > +			no-map;
> > > > +			reg = <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
> > > > +			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
> > > > +		};
> > > > +
> > > > +		mbox-buf@06dff000 {
> > > > +			no-map;
> > > > +			reg = <0x0 0x06dff000 0x0 0x00001000>;	/* Mailbox message buf */
> > > > +		};
> > > > +	};
> > > 
> > > As far as I can see, it would be simpler to simply carve these out of the
> > > memory node.
> > > 
> > > I don't see why you need reserved-memory here, given you're not referring to
> > > these regions by phandle anyway.
> > 
> > - Now we have enabled EFI_STUB, so the memory node will be removed in
> >   kernel:
> >     efi_entry()
> >       \-> allocate_new_fdt_and_exit_boot()
> >             \-> update_fdt();
> > 
> >   Finally in kernel it cannot use memory node to carve out reseved
> >   memory regions.
> > 
> > - On the other hand, DTS's the memory node is to "describes the
> >   physical memory layout for the system"; so it's better to use it only
> >   to describe the hardware info for memory. We can use reserved-memory
> >   to help manage the memory regions which are reserved from software
> >   perspective.
> 
> The fact that you have no-map means that the memory should not be
> described to the kernel as mappable in the first place. It's wrong to
> place such memory in the memory node, even if listed in reserved-memory.
> 
> If your EFI memory map describes the memory as mappable, it is wrong.

When kernel is working, kernel will create its own page table based on
UEFI memory map. Since it's reserved in DTS file as Leo's patch, it'll
be moved to reserved memblock. Why is it wrong?

In the second, UEFI is firmware. When it's stable, nobody should change
it without any reason. These reserved memory are used in mailbox driver.
Look. It's driver, so it could be changed at any time. Why do you want
to UEFI knowing this memory range? Do you hope UEFI to change when
mailbox driver is changed?

> 
> > According to upper info, we still need to use reserved-memory node to
> > depict the reserved memory regions. i have no knowledge about EFI_STUB,
> > so please confirm or correct as needed.
> 
> If the memory shouldn't be mapped, it should neither be in the memory
> node nor EFI memory map (with attributes allowing it to be mapped) to
> begin with.

As I said above, kernel will create its own page table. When kernel's
page table is working, UEFI's page table is destroying. So the memory
won't be mapped twice at the same time. What's wrong?
> 
> As far as I can see you do not need to use reserved-memory.

1. Are we talking on the same thing? Leo already mentioned that all
memory node in DTB will be destroyed by kernel when EFI_STUB is enabled
on arm. Did you read the source code after his reply?
And you suggested that Leo to use discrete memory region in DTB. It is
really wrong. Kernel only gets memory map information from UEFI, not
DTB.

2. The working flow is in below.
   a. Kernel gets memory map information from UEFI.
   b. Kernel loads the memory reserved information from DTB.

3. Do you mean the reserved-memory is totally wrong? If it's wrong,
please submit patches to remove all reserved-memory in linux kernel
first.

4. Again and again. Memory node should be only used to describe the
RAM information.

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#1212092

On Mon, Aug 24, 2015 at 06:19:56PM +0800, Haojian Zhuang wrote:
> > If your EFI memory map describes the memory as mappable, it is wrong.
> 
> When kernel is working, kernel will create its own page table based on
> UEFI memory map. Since it's reserved in DTS file as Leo's patch, it'll
> be moved to reserved memblock. Why is it wrong?
> 
> In the second, UEFI is firmware. When it's stable, nobody should change
> it without any reason.

Much like the memory map.

> These reserved memory are used in mailbox driver.
> Look. It's driver, so it could be changed at any time.

No, it is a set of regions of memory set aside for use by a different
master in the system as well as communications with that master.

The fact that there is a driver somewhere that is aware of this is
entirely beside the point. All agents in the system must adher to this
protocol.

> Why do you want
> to UEFI knowing this memory range? Do you hope UEFI to change when
> mailbox driver is changed?

Yes.

UEFI is a runtime environment. Having random magic areas not to be
touched will cause random pieces of software running under it to break
horribly or break other things horribly.
Unless you mark them as reserved in the UEFI memory map.
At which point the Linux kernel will automatically ignore them, and
the proposed patch is redundant.

So, yes, if you want a system that can boot reliably, run testsuites
(like SCT or FWTS), run applications (like fastboot ... or the EFI
stub kernel itself), then any memory regions that is reserved for
mailbox communication (or other masters in the system) _must_ be
marked in the EFI memory map.

/
    Leif
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#1212797

On Mon, 2015-08-24 at 12:49 +0100, Leif Lindholm wrote:
> On Mon, Aug 24, 2015 at 06:19:56PM +0800, Haojian Zhuang wrote:
> > > If your EFI memory map describes the memory as mappable, it is wrong.
> > 
> > When kernel is working, kernel will create its own page table based on
> > UEFI memory map. Since it's reserved in DTS file as Leo's patch, it'll
> > be moved to reserved memblock. Why is it wrong?
> > 
> > In the second, UEFI is firmware. When it's stable, nobody should change
> > it without any reason.
> 
> Much like the memory map.
> 
> > These reserved memory are used in mailbox driver.
> > Look. It's driver, so it could be changed at any time.
> 
> No, it is a set of regions of memory set aside for use by a different
> master in the system as well as communications with that master.
> 
> The fact that there is a driver somewhere that is aware of this is
> entirely beside the point. All agents in the system must adher to this
> protocol.
> 
> > Why do you want
> > to UEFI knowing this memory range? Do you hope UEFI to change when
> > mailbox driver is changed?
> 
> Yes.
> 
> UEFI is a runtime environment. Having random magic areas not to be
> touched will cause random pieces of software running under it to break
> horribly or break other things horribly.
> Unless you mark them as reserved in the UEFI memory map.
> At which point the Linux kernel will automatically ignore them, and
> the proposed patch is redundant.
> 
> So, yes, if you want a system that can boot reliably, run testsuites
> (like SCT or FWTS), run applications (like fastboot ... or the EFI
> stub kernel itself), then any memory regions that is reserved for
> mailbox communication (or other masters in the system) _must_ be
> marked in the EFI memory map.

1. We need support both UEFI and uboot. So the reserved buffer have to
be declared in DTB since they are used by kernel driver, not UEFI.

2. UEFI just loads grub. It's no time to run any other custom EFI
application.

Regards
Haojian

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#1212916

On Tue, Aug 25, 2015 at 04:13:47PM +0800, Haojian Zhuang wrote:
> On Mon, 2015-08-24 at 12:49 +0100, Leif Lindholm wrote:
> > On Mon, Aug 24, 2015 at 06:19:56PM +0800, Haojian Zhuang wrote:
> > > > If your EFI memory map describes the memory as mappable, it is wrong.
> > > 
> > > When kernel is working, kernel will create its own page table based on
> > > UEFI memory map. Since it's reserved in DTS file as Leo's patch, it'll
> > > be moved to reserved memblock. Why is it wrong?
> > > 
> > > In the second, UEFI is firmware. When it's stable, nobody should change
> > > it without any reason.
> > 
> > Much like the memory map.
> > 
> > > These reserved memory are used in mailbox driver.
> > > Look. It's driver, so it could be changed at any time.
> > 
> > No, it is a set of regions of memory set aside for use by a different
> > master in the system as well as communications with that master.
> > 
> > The fact that there is a driver somewhere that is aware of this is
> > entirely beside the point. All agents in the system must adher to this
> > protocol.
> > 
> > > Why do you want
> > > to UEFI knowing this memory range? Do you hope UEFI to change when
> > > mailbox driver is changed?
> > 
> > Yes.
> > 
> > UEFI is a runtime environment. Having random magic areas not to be
> > touched will cause random pieces of software running under it to break
> > horribly or break other things horribly.
> > Unless you mark them as reserved in the UEFI memory map.
> > At which point the Linux kernel will automatically ignore them, and
> > the proposed patch is redundant.
> > 
> > So, yes, if you want a system that can boot reliably, run testsuites
> > (like SCT or FWTS), run applications (like fastboot ... or the EFI
> > stub kernel itself), then any memory regions that is reserved for
> > mailbox communication (or other masters in the system) _must_ be
> > marked in the EFI memory map.
> 
> 1. We need support both UEFI and uboot. So the reserved buffer have to
> be declared in DTB since they are used by kernel driver, not UEFI.

The buffer may need to be declared in DTB also, but it most certanily
needs to be declared in UEFI.

And for the U-Boot case, since it is not memory available to Linux, it
should not be declared as "memory".

> 2. UEFI just loads grub. It's no time to run any other custom EFI
> application.

Apart from being completely irrelevant, how are you intending to
validate that GRUB never touches these memory regions?

Build a version once, test it, and hope the results remain valid
forever? And then when you move the regions and the previously working
GRUB now tramples all over them? Or when something changes in upstream
GRUB and its memory allocations drifts into the secretly untouchable
regions?

Are you then going to hack GRUB, release a special HiKey version of
GRUB, not support any other versions, and still can your firmware
UEFI?

Repeat again and again for any other UEFI applications - including
fastboot, SCT, FWTS and the UEFI stub kernel.

/
    Leif
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#1212928

On Tue, 2015-08-25 at 10:46 +0100, Leif Lindholm wrote:
> On Tue, Aug 25, 2015 at 04:13:47PM +0800, Haojian Zhuang wrote:
> > On Mon, 2015-08-24 at 12:49 +0100, Leif Lindholm wrote:
> > > On Mon, Aug 24, 2015 at 06:19:56PM +0800, Haojian Zhuang wrote:
> > > > > If your EFI memory map describes the memory as mappable, it is wrong.
> > > > 
> > > > When kernel is working, kernel will create its own page table based on
> > > > UEFI memory map. Since it's reserved in DTS file as Leo's patch, it'll
> > > > be moved to reserved memblock. Why is it wrong?
> > > > 
> > > > In the second, UEFI is firmware. When it's stable, nobody should change
> > > > it without any reason.
> > > 
> > > Much like the memory map.
> > > 
> > > > These reserved memory are used in mailbox driver.
> > > > Look. It's driver, so it could be changed at any time.
> > > 
> > > No, it is a set of regions of memory set aside for use by a different
> > > master in the system as well as communications with that master.
> > > 
> > > The fact that there is a driver somewhere that is aware of this is
> > > entirely beside the point. All agents in the system must adher to this
> > > protocol.
> > > 
> > > > Why do you want
> > > > to UEFI knowing this memory range? Do you hope UEFI to change when
> > > > mailbox driver is changed?
> > > 
> > > Yes.
> > > 
> > > UEFI is a runtime environment. Having random magic areas not to be
> > > touched will cause random pieces of software running under it to break
> > > horribly or break other things horribly.
> > > Unless you mark them as reserved in the UEFI memory map.
> > > At which point the Linux kernel will automatically ignore them, and
> > > the proposed patch is redundant.
> > > 
> > > So, yes, if you want a system that can boot reliably, run testsuites
> > > (like SCT or FWTS), run applications (like fastboot ... or the EFI
> > > stub kernel itself), then any memory regions that is reserved for
> > > mailbox communication (or other masters in the system) _must_ be
> > > marked in the EFI memory map.
> > 
> > 1. We need support both UEFI and uboot. So the reserved buffer have to
> > be declared in DTB since they are used by kernel driver, not UEFI.
> 
> The buffer may need to be declared in DTB also, but it most certanily
> needs to be declared in UEFI.
> 
> And for the U-Boot case, since it is not memory available to Linux, it
> should not be declared as "memory".

Something are messed at here. We have these buffer are used in mailbox.
They should be allocated as non-cacheable.

If these buffers are contained in memory memblock in kernel, it means
that they exist in kernel page table with cachable property. When it's
used in mailbox driver with non-cachable property, it'll only cause
cache maintenance issue. So Leo declared these buffers as reserved
in DT with "no-map" property. It's the key. It could avoid the cache
maintenance issue.

> 
> > 2. UEFI just loads grub. It's no time to run any other custom EFI
> > application.
> 
> Apart from being completely irrelevant, how are you intending to
> validate that GRUB never touches these memory regions?
> 

GRUB is just a part of bootloader. When linux kernel is running,
who cares GRUB? GRUB's lifetime is already finished.

By the way, UEFI code region is at [0x3Dxx_xxxx, 0x3DFF_FFFF]. Those
mailbox buffer is in [0x05e0_xxxx, 0x06f0_xxxx]. Then I can make sure
UEFI won't touch the reserved buffer. Even if UEFI touched the reserved
buffer, is it an issue? Definitely it's not. UEFI's lifetime is end
when linux kernel is running at hikey. Even if UEFI runtime service
is enabled, the runtime data area is at [0x38xx_xxxx, 0x38xx_xxxx].

> Build a version once, test it, and hope the results remain valid
> forever? And then when you move the regions and the previously working
> GRUB now tramples all over them? Or when something changes in upstream
> GRUB and its memory allocations drifts into the secretly untouchable
> regions?

As I said above, UEFI won't touch it. And even UEFI touch it, kernel
doesn't care since UEFI's lifetime is end.

> 
> Are you then going to hack GRUB, release a special HiKey version of
> GRUB, not support any other versions, and still can your firmware
> UEFI?

I don't need to hack GRUB at all.

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#1212945

On Tue, Aug 25, 2015 at 06:15:10PM +0800, Haojian Zhuang wrote:
> > > 1. We need support both UEFI and uboot. So the reserved buffer have to
> > > be declared in DTB since they are used by kernel driver, not UEFI.
> > 
> > The buffer may need to be declared in DTB also, but it most certanily
> > needs to be declared in UEFI.
> > 
> > And for the U-Boot case, since it is not memory available to Linux, it
> > should not be declared as "memory".
> 
> Something are messed at here. We have these buffer are used in mailbox.
> They should be allocated as non-cacheable.

That is a completely different issue, and if that is not currently
possible, then we need to fix that. But it needs to be fixed in the
right place.

> If these buffers are contained in memory memblock in kernel, it means
> that they exist in kernel page table with cachable property. When it's
> used in mailbox driver with non-cachable property, it'll only cause
> cache maintenance issue. So Leo declared these buffers as reserved
> in DT with "no-map" property. It's the key. It could avoid the cache
> maintenance issue.

Yes, when not booting with UEFI.

> > > 2. UEFI just loads grub. It's no time to run any other custom EFI
> > > application.
> > 
> > Apart from being completely irrelevant, how are you intending to
> > validate that GRUB never touches these memory regions?
> 
> GRUB is just a part of bootloader. When linux kernel is running,
> who cares GRUB? GRUB's lifetime is already finished.

We don't care once Linux is running - we care between UEFI boot
services starting and Linux memblock being initialised.

> By the way, UEFI code region is at [0x3Dxx_xxxx, 0x3DFF_FFFF]. Those
> mailbox buffer is in [0x05e0_xxxx, 0x06f0_xxxx]. Then I can make sure
> UEFI won't touch the reserved buffer.

And if a UEFI application explicitly requests to map an area
elsewhere, will your UEFI reject that request? How will it do that
without having information in its memory map about areas it must not
access?

> Even if UEFI touched the reserved
> buffer, is it an issue? Definitely it's not. UEFI's lifetime is end
> when linux kernel is running at hikey. Even if UEFI runtime service
> is enabled, the runtime data area is at [0x38xx_xxxx, 0x38xx_xxxx].

The runtime data area is currently, in your current image, at
[0x38xx_xxxx, 0x38xx_xxxx].

What happens if a UEFI application registers a configuration table?
Or registers a protocol for use at runtime?

Areas of memory that are not available for UEFI _must_ be marked as
such in the UEFI memory map. Once they are, we can deal with them in
the kernel. If this is not currently being done, that is a bug that
needs fixing.

> > Build a version once, test it, and hope the results remain valid
> > forever? And then when you move the regions and the previously working
> > GRUB now tramples all over them? Or when something changes in upstream
> > GRUB and its memory allocations drifts into the secretly untouchable
> > regions?
> 
> As I said above, UEFI won't touch it. And even UEFI touch it, kernel
> doesn't care since UEFI's lifetime is end.

UEFI's lifetime doesn't end until reset.

> > Are you then going to hack GRUB, release a special HiKey version of
> > GRUB, not support any other versions, and still can your firmware
> > UEFI?
> 
> I don't need to hack GRUB at all.

You will if you're running it under a "UEFI" which has areas you can't
touch and aren't telling it about that.

/
    Leif
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#1212951

On Tue, Aug 25, 2015 at 11:15:10AM +0100, Haojian Zhuang wrote:
> On Tue, 2015-08-25 at 10:46 +0100, Leif Lindholm wrote:
> > On Tue, Aug 25, 2015 at 04:13:47PM +0800, Haojian Zhuang wrote:
> > > On Mon, 2015-08-24 at 12:49 +0100, Leif Lindholm wrote:
> > > > On Mon, Aug 24, 2015 at 06:19:56PM +0800, Haojian Zhuang wrote:
> > > > > > If your EFI memory map describes the memory as mappable, it is wrong.
> > > > > 
> > > > > When kernel is working, kernel will create its own page table based on
> > > > > UEFI memory map. Since it's reserved in DTS file as Leo's patch, it'll
> > > > > be moved to reserved memblock. Why is it wrong?
> > > > > 
> > > > > In the second, UEFI is firmware. When it's stable, nobody should change
> > > > > it without any reason.
> > > > 
> > > > Much like the memory map.
> > > > 
> > > > > These reserved memory are used in mailbox driver.
> > > > > Look. It's driver, so it could be changed at any time.
> > > > 
> > > > No, it is a set of regions of memory set aside for use by a different
> > > > master in the system as well as communications with that master.
> > > > 
> > > > The fact that there is a driver somewhere that is aware of this is
> > > > entirely beside the point. All agents in the system must adher to this
> > > > protocol.
> > > > 
> > > > > Why do you want
> > > > > to UEFI knowing this memory range? Do you hope UEFI to change when
> > > > > mailbox driver is changed?
> > > > 
> > > > Yes.
> > > > 
> > > > UEFI is a runtime environment. Having random magic areas not to be
> > > > touched will cause random pieces of software running under it to break
> > > > horribly or break other things horribly.
> > > > Unless you mark them as reserved in the UEFI memory map.
> > > > At which point the Linux kernel will automatically ignore them, and
> > > > the proposed patch is redundant.
> > > > 
> > > > So, yes, if you want a system that can boot reliably, run testsuites
> > > > (like SCT or FWTS), run applications (like fastboot ... or the EFI
> > > > stub kernel itself), then any memory regions that is reserved for
> > > > mailbox communication (or other masters in the system) _must_ be
> > > > marked in the EFI memory map.
> > > 
> > > 1. We need support both UEFI and uboot. So the reserved buffer have to
> > > be declared in DTB since they are used by kernel driver, not UEFI.
> > 
> > The buffer may need to be declared in DTB also, but it most certanily
> > needs to be declared in UEFI.
> > 
> > And for the U-Boot case, since it is not memory available to Linux, it
> > should not be declared as "memory".
> 
> Something are messed at here. We have these buffer are used in mailbox.
> They should be allocated as non-cacheable.
> 
> If these buffers are contained in memory memblock in kernel, it means
> that they exist in kernel page table with cachable property. When it's
> used in mailbox driver with non-cachable property, it'll only cause
> cache maintenance issue. So Leo declared these buffers as reserved
> in DT with "no-map" property. It's the key. It could avoid the cache
> maintenance issue.

The better solution is to never describe the memory to the kernel as
memory, by never placing it in a memory node, and ensuring that if it is
in the UEFI memory map, its attributes do not allow it to be mapped.

That way a driver can map it as non-cacheable if it wishes, but nothing
else can possibly touch that memory.

That is all you need to do.

> > > 2. UEFI just loads grub. It's no time to run any other custom EFI
> > > application.
> > 
> > Apart from being completely irrelevant, how are you intending to
> > validate that GRUB never touches these memory regions?
> > 
> 
> GRUB is just a part of bootloader. When linux kernel is running,
> who cares GRUB? GRUB's lifetime is already finished.

If GRUB temporarily maps memory as cacheable, or hands it to a device,
then your statements above about cache maintenance are broken.

An EFI application like GRUB might leave something resident in memory
after it's done (consider the UEFI shim), or it could even load the
kernel into the region that you care about having reserved, because as
far as it's concerned it's just memory. That could leave you with a
conflict for that region of memory.

You _must_ care about GRUB (and other EFI applications) doing the right
thing. To get them to avoid a region of memory, it must not be described
as being usable by them in the UEFI memory map.

> By the way, UEFI code region is at [0x3Dxx_xxxx, 0x3DFF_FFFF]. Those
> mailbox buffer is in [0x05e0_xxxx, 0x06f0_xxxx]. Then I can make sure
> UEFI won't touch the reserved buffer. Even if UEFI touched the reserved
> buffer, is it an issue? Definitely it's not.

It definitely is, due to the possibility of stale cache lines being left
in the region from when UEFI may have mapped it with cacheable
attributes.

> > Build a version once, test it, and hope the results remain valid
> > forever? And then when you move the regions and the previously working
> > GRUB now tramples all over them? Or when something changes in upstream
> > GRUB and its memory allocations drifts into the secretly untouchable
> > regions?
> 
> As I said above, UEFI won't touch it. And even UEFI touch it, kernel
> doesn't care since UEFI's lifetime is end.

If EFI touches it there may be stale cache lines left around, which you
don't seem to expect.

> > Are you then going to hack GRUB, release a special HiKey version of
> > GRUB, not support any other versions, and still can your firmware
> > UEFI?
> 
> I don't need to hack GRUB at all.

Then it is working for you by pure chance alone.

Please listen to the advice you are being given here; we're trying to
ensure that your platform functions (and continues to function) as best
it can.

Thanks,
Mark.
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#1213045

On Tue, 2015-08-25 at 11:42 +0100, Mark Rutland wrote:
> > > Are you then going to hack GRUB, release a special HiKey version of
> > > GRUB, not support any other versions, and still can your firmware
> > > UEFI?
> > 
> > I don't need to hack GRUB at all.
> 
> Then it is working for you by pure chance alone.
> 
> Please listen to the advice you are being given here; we're trying to
> ensure that your platform functions (and continues to function) as best
> it can.

Since we discussed a lot on this, let's make a conclusion on it.

1. UEFI could append the reserved buffer in it's memory mapping.
2. These reserved buffer must be declared in DT, since we also need to
   support non-UEFI (uboot) at the same time.
3. Mailbox node should reference reserved buffer by phandle in DT. Then
   map the buffer as non-cacheable in driver.
4. These reserved buffer must use "no-map" property since it should be
   non-cacheable in driver.
5. A patch is necessary in kernel. If efi stub feature is enabled,
   arm kernel should not parse memory node or reserved memory buffer in
   DT any more. Arm kernel should either fetch memory information from 
   efi or DT. Currently arm kernel fetch both efi memory information and
   reserved buffer from DTB at the same time.

Do you agree on these points?

Regards
Haojian

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#1213081

On Tue, Aug 25, 2015 at 09:43:14PM +0800, Haojian Zhuang wrote:
> Since we discussed a lot on this, let's make a conclusion on it.
> 
> 1. UEFI could append the reserved buffer in it's memory mapping.

Yes. It needs to.

(I will let Mark comment on points 2-4.)

> 5. A patch is necessary in kernel. If efi stub feature is enabled,
>    arm kernel should not parse memory node or reserved memory buffer in
>    DT any more.

This is already the case. The stub deletes any present memory nodes and
reserved entries in drivers/firmware/efi/libstub/fdt.c:update_fdt().

Then, during setup_arch(), arch/arm64/kernel/efi.c:efi_init() calls
reserve_regions(), which adds only those memory regions available for
use by Linux as RAM to memblock.

>    Arm kernel should either fetch memory information from 
>    efi or DT.

Absolutely.

>    Currently arm kernel fetch both efi memory information and
>    reserved buffer from DTB at the same time.

No, it does not.

Regards,

Leif
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#1213094

On 25 August 2015 at 16:24, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> On Tue, Aug 25, 2015 at 09:43:14PM +0800, Haojian Zhuang wrote:
>> Since we discussed a lot on this, let's make a conclusion on it.
>>
>> 1. UEFI could append the reserved buffer in it's memory mapping.
>
> Yes. It needs to.
>
> (I will let Mark comment on points 2-4.)
>
>> 5. A patch is necessary in kernel. If efi stub feature is enabled,
>>    arm kernel should not parse memory node or reserved memory buffer in
>>    DT any more.
>
> This is already the case. The stub deletes any present memory nodes and
> reserved entries in drivers/firmware/efi/libstub/fdt.c:update_fdt().
>
> Then, during setup_arch(), arch/arm64/kernel/efi.c:efi_init() calls
> reserve_regions(), which adds only those memory regions available for
> use by Linux as RAM to memblock.
>
>>    Arm kernel should either fetch memory information from
>>    efi or DT.
>
> Absolutely.
>
>>    Currently arm kernel fetch both efi memory information and
>>    reserved buffer from DTB at the same time.
>
> No, it does not.
>

It should not, but it does. Due to an oversight, the stub removes
/memreserve/ entries but ignores the reserved-memory node completely.

This was reported here in fact

http://thread.gmane.org/gmane.linux.kernel.efi/5736/focus=5742

but there has not been a followup to this series.

I think it is fine to keep those memory reservations in the DT, but
you should simply understand that UEFI does not parse the DT, so you
need to tell it which memory it cannot touch. Otherwise, the firmware
itself or anything that executes under it (UEFI drivers, the UEFI
Shell, GRUB, the UEFI stub in the kernel) will think it is available
and may allocate it for its own use. This may include runtime services
regions that will remain reserved even after exiting boot services.

-- 
Ard.
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#1213120

On Tue, Aug 25, 2015 at 04:51:22PM +0200, Ard Biesheuvel wrote:
> >>    Arm kernel should either fetch memory information from
> >>    efi or DT.
> >
> > Absolutely.
> >
> >>    Currently arm kernel fetch both efi memory information and
> >>    reserved buffer from DTB at the same time.
> >
> > No, it does not.
> 
> It should not, but it does. Due to an oversight, the stub removes
> /memreserve/ entries but ignores the reserved-memory node completely.

Urgh.

> This was reported here in fact
> 
> http://thread.gmane.org/gmane.linux.kernel.efi/5736/focus=5742
> 
> but there has not been a followup to this series.

Are all of those patches still relevant, or did some of them go in
already?

Haojian: can you give that patch a spin and see if it does what you
need, combined with adding the reserved areas to the UEFI memory map?

/
    Leif
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#1213126

On 25 August 2015 at 17:37, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> On Tue, Aug 25, 2015 at 04:51:22PM +0200, Ard Biesheuvel wrote:
>> >>    Arm kernel should either fetch memory information from
>> >>    efi or DT.
>> >
>> > Absolutely.
>> >
>> >>    Currently arm kernel fetch both efi memory information and
>> >>    reserved buffer from DTB at the same time.
>> >
>> > No, it does not.
>>
>> It should not, but it does. Due to an oversight, the stub removes
>> /memreserve/ entries but ignores the reserved-memory node completely.
>
> Urgh.
>
>> This was reported here in fact
>>
>> http://thread.gmane.org/gmane.linux.kernel.efi/5736/focus=5742
>>
>> but there has not been a followup to this series.
>
> Are all of those patches still relevant, or did some of them go in
> already?
>

The first two patches are in v4.2-rc1 and up, the others should still
apply on top of that.

-- 
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#1213505

On Tue, 2015-08-25 at 16:37 +0100, Leif Lindholm wrote:
> On Tue, Aug 25, 2015 at 04:51:22PM +0200, Ard Biesheuvel wrote:
> > >>    Arm kernel should either fetch memory information from
> > >>    efi or DT.
> > >
> > > Absolutely.
> > >
> > >>    Currently arm kernel fetch both efi memory information and
> > >>    reserved buffer from DTB at the same time.
> > >
> > > No, it does not.
> > 
> > It should not, but it does. Due to an oversight, the stub removes
> > /memreserve/ entries but ignores the reserved-memory node completely.
> 
> Urgh.
> 
> > This was reported here in fact
> > 
> > http://thread.gmane.org/gmane.linux.kernel.efi/5736/focus=5742
> > 
> > but there has not been a followup to this series.
> 
> Are all of those patches still relevant, or did some of them go in
> already?
> 
> Haojian: can you give that patch a spin and see if it does what you
> need, combined with adding the reserved areas to the UEFI memory map?
> 
> /
>     Leif

It's so nice. This patch is what I need.

Thanks
Haojian

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#1213135

On Tue, Aug 25, 2015 at 09:43:14PM +0800, Haojian Zhuang wrote:
> On Tue, 2015-08-25 at 11:42 +0100, Mark Rutland wrote:
> > > > Are you then going to hack GRUB, release a special HiKey version of
> > > > GRUB, not support any other versions, and still can your firmware
> > > > UEFI?
> > > 
> > > I don't need to hack GRUB at all.
> > 
> > Then it is working for you by pure chance alone.
> > 
> > Please listen to the advice you are being given here; we're trying to
> > ensure that your platform functions (and continues to function) as best
> > it can.
> 
> Since we discussed a lot on this, let's make a conclusion on it.
> 
> 1. UEFI could append the reserved buffer in it's memory mapping.
> 2. These reserved buffer must be declared in DT, since we also need to
>    support non-UEFI (uboot) at the same time.
> 3. Mailbox node should reference reserved buffer by phandle in DT. Then
>    map the buffer as non-cacheable in driver.
> 4. These reserved buffer must use "no-map" property since it should be
>    non-cacheable in driver.

For more specific discussion for DTS, i list two options at here;

- Option 1: just simply reserve memory regions through memory node,
  and mailbox node will directly use the buffer through reg ranges;

- Option 2: use reserved-memory and mailbox node will refer phandle
  of reserved-memory;

These two options both can work well with UEFI and Uboot, but option 1
is more simple and straightforward; so i personally prefer it. But
look forwarding your guys' suggestion.

Option 1:

	memory@0 {
		device_type = "memory";
		reg = <0x00000000 0x00000000 0x00000000 0x05e00000>,
		      <0x00000000 0x05f00000 0x00000000 0x00eff000>,
		      <0x00000000 0x06e00000 0x00000000 0x0060f000>,
		      <0x00000000 0x07410000 0x00000000 0x38bf0000>;
	};

        [...]

	mailbox: mailbox@f7510000 {
		#mbox-cells = <1>;
		compatible = "hisilicon,hi6220-mbox";
		reg = <0x0 0xf7510000 0x0 0x1000>, /* IPC_S */
		      <0x0 0x06dff800 0x0 0x0800>; /* Mailbox buffer */
		interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
	};

Option 2:

	memory@0 {
		device_type = "memory";
		reg = <0x0 0x0 0x0 0x40000000>;
	};

	reserved-memory {
		#address-cells = <2>;
		#size-cells = <2>;
		ranges;

		mcu_reserved: mcu_reserved@06dff000 {
			no-map;
			reg = <0x0 0x06dff000 0x0 0x00001000>,	/* MCU mailbox buffer */
			      <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
		};
	};

        [...]

	mailbox: mailbox@f7510000 {
		#mbox-cells = <1>;
		compatible = "hisilicon,hi6220-mbox";
		reg = <0x0 0xf7510000 0x0 0x1000>; /* IPC_S */
		memory-region = <&mcu_reserved>;   /* Mailbox buffer */
		interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
	};


> 5. A patch is necessary in kernel. If efi stub feature is enabled,
>    arm kernel should not parse memory node or reserved memory buffer in
>    DT any more. Arm kernel should either fetch memory information from 
>    efi or DT. Currently arm kernel fetch both efi memory information and
>    reserved buffer from DTB at the same time.
> 
> Do you agree on these points?
> 
> Regards
> Haojian
> 
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#1213471

On Wed, 2015-08-26 at 00:00 +0800, Leo Yan wrote:
> On Tue, Aug 25, 2015 at 09:43:14PM +0800, Haojian Zhuang wrote:
> > On Tue, 2015-08-25 at 11:42 +0100, Mark Rutland wrote:
> > > > > Are you then going to hack GRUB, release a special HiKey version of
> > > > > GRUB, not support any other versions, and still can your firmware
> > > > > UEFI?
> > > > 
> > > > I don't need to hack GRUB at all.
> > > 
> > > Then it is working for you by pure chance alone.
> > > 
> > > Please listen to the advice you are being given here; we're trying to
> > > ensure that your platform functions (and continues to function) as best
> > > it can.
> > 
> > Since we discussed a lot on this, let's make a conclusion on it.
> > 
> > 1. UEFI could append the reserved buffer in it's memory mapping.
> > 2. These reserved buffer must be declared in DT, since we also need to
> >    support non-UEFI (uboot) at the same time.
> > 3. Mailbox node should reference reserved buffer by phandle in DT. Then
> >    map the buffer as non-cacheable in driver.
> > 4. These reserved buffer must use "no-map" property since it should be
> >    non-cacheable in driver.
> 
> For more specific discussion for DTS, i list two options at here;
> 
> - Option 1: just simply reserve memory regions through memory node,
>   and mailbox node will directly use the buffer through reg ranges;
> 
> - Option 2: use reserved-memory and mailbox node will refer phandle
>   of reserved-memory;
> 
> These two options both can work well with UEFI and Uboot, but option 1
> is more simple and straightforward; so i personally prefer it. But
> look forwarding your guys' suggestion.
> 
> Option 1:
> 
> 	memory@0 {
> 		device_type = "memory";
> 		reg = <0x00000000 0x00000000 0x00000000 0x05e00000>,
> 		      <0x00000000 0x05f00000 0x00000000 0x00eff000>,
> 		      <0x00000000 0x06e00000 0x00000000 0x0060f000>,
> 		      <0x00000000 0x07410000 0x00000000 0x38bf0000>;
> 	};
> 
>         [...]
> 
> 	mailbox: mailbox@f7510000 {
> 		#mbox-cells = <1>;
> 		compatible = "hisilicon,hi6220-mbox";
> 		reg = <0x0 0xf7510000 0x0 0x1000>, /* IPC_S */
> 		      <0x0 0x06dff800 0x0 0x0800>; /* Mailbox buffer */
> 		interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
> 	};
> 
> Option 2:
> 
> 	memory@0 {
> 		device_type = "memory";
> 		reg = <0x0 0x0 0x0 0x40000000>;
> 	};
> 
> 	reserved-memory {
> 		#address-cells = <2>;
> 		#size-cells = <2>;
> 		ranges;
> 
> 		mcu_reserved: mcu_reserved@06dff000 {
> 			no-map;
> 			reg = <0x0 0x06dff000 0x0 0x00001000>,	/* MCU mailbox buffer */
> 			      <0x0 0x05e00000 0x0 0x00100000>,	/* MCU firmware buffer */
> 			      <0x0 0x0740f000 0x0 0x00001000>;	/* MCU firmware section */
> 		};
> 	};
> 
>         [...]
> 
> 	mailbox: mailbox@f7510000 {
> 		#mbox-cells = <1>;
> 		compatible = "hisilicon,hi6220-mbox";
> 		reg = <0x0 0xf7510000 0x0 0x1000>; /* IPC_S */
> 		memory-region = <&mcu_reserved>;   /* Mailbox buffer */
> 		interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
> 	};

I prefer the second one. From my view, memory node should only describe
the hardware information of memory.

Regards
Haojian

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