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Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and {min,max}_low_pfn

Started byGreg Ungerer <gerg@uclinux.org>
First post2015-11-16 13:20 +0100
Last post2015-11-17 00:50 +0100
Articles 3 — 2 participants

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  Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and  {min,max}_low_pfn Greg Ungerer <gerg@uclinux.org> - 2015-11-16 13:20 +0100
    Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and {min,max}_low_pfn Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-16 14:10 +0100
      Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and  {min,max}_low_pfn Greg Ungerer <gerg@uclinux.org> - 2015-11-17 00:50 +0100

#1270057 — Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and {min,max}_low_pfn

FromGreg Ungerer <gerg@uclinux.org>
Date2015-11-16 13:20 +0100
SubjectRe: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and {min,max}_low_pfn
Message-ID<qvqVk-7cN-17@gated-at.bofh.it>
Hi Geert,

On 15/11/15 21:04, Geert Uytterhoeven wrote:
> If max_pfn is not initialized, the block layer may use wrong DMA masks.
>
> Replace open-coded shifts by PFN_DOWN() while we're at it.
>
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> Compile-tested only.
> ---
>   arch/m68k/kernel/setup_no.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/m68k/kernel/setup_no.c b/arch/m68k/kernel/setup_no.c
> index 88c27d94a7214c95..29b44e69f0f47375 100644
> --- a/arch/m68k/kernel/setup_no.c
> +++ b/arch/m68k/kernel/setup_no.c
> @@ -238,11 +238,14 @@ void __init setup_arch(char **cmdline_p)
>   	 * Give all the memory to the bootmap allocator, tell it to put the
>   	 * boot mem_map at the start of memory.
>   	 */
> +	min_low_pfn = PFN_DOWN(memory_start);
> +	max_pfn = max_low_pfn = PFN_DOWN(memory_end);
> +
>   	bootmap_size = init_bootmem_node(
>   			NODE_DATA(0),
> -			memory_start >> PAGE_SHIFT, /* map goes here */
> -			PAGE_OFFSET >> PAGE_SHIFT,	/* 0 on coldfire */
> -			memory_end >> PAGE_SHIFT);
> +			min_low_pfn,		/* map goes here */
> +			PFN_DOWN(PAGE_OFFSET),	/* 0 on coldfire */
> +			max_pfn);
>   	/*
>   	 * Free the usable memory, we have to make sure we do not free
>   	 * the bootmem bitmap so we then reserve it after freeing it :-)

Should this be changed to use init_bootmem() as per your changes
in patch 3 ("m68k/mm: sun3 - Add missing initialization of max_pfn and 
{min,max}_low_pfn")? For the same reason?

Regards
Greg


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#1270103 — Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and {min,max}_low_pfn

FromGeert Uytterhoeven <geert@linux-m68k.org>
Date2015-11-16 14:10 +0100
SubjectRe: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and {min,max}_low_pfn
Message-ID<qvrHI-7IR-13@gated-at.bofh.it>
In reply to#1270057
Hi Greg,

On Mon, Nov 16, 2015 at 1:18 PM, Greg Ungerer <gerg@uclinux.org> wrote:
>> --- a/arch/m68k/kernel/setup_no.c
>> +++ b/arch/m68k/kernel/setup_no.c
>> @@ -238,11 +238,14 @@ void __init setup_arch(char **cmdline_p)
>>          * Give all the memory to the bootmap allocator, tell it to put
>> the
>>          * boot mem_map at the start of memory.
>>          */
>> +       min_low_pfn = PFN_DOWN(memory_start);
>> +       max_pfn = max_low_pfn = PFN_DOWN(memory_end);
>> +
>>         bootmap_size = init_bootmem_node(
>>                         NODE_DATA(0),
>> -                       memory_start >> PAGE_SHIFT, /* map goes here */
>> -                       PAGE_OFFSET >> PAGE_SHIFT,      /* 0 on coldfire
>> */
>> -                       memory_end >> PAGE_SHIFT);
>> +                       min_low_pfn,            /* map goes here */
>> +                       PFN_DOWN(PAGE_OFFSET),  /* 0 on coldfire */
>> +                       max_pfn);
>>         /*
>>          * Free the usable memory, we have to make sure we do not free
>>          * the bootmem bitmap so we then reserve it after freeing it :-)
>
> Should this be changed to use init_bootmem() as per your changes
> in patch 3 ("m68k/mm: sun3 - Add missing initialization of max_pfn and
> {min,max}_low_pfn")? For the same reason?

No. PAGE_OFFSET = PAGE_OFFSET_RAW = CONFIG_RAMBASE.
As the comment says, this is zero on coldfire, but not on all m68knommu
platforms.

Upon closer look, this isn't even true on all Coldfire boards:

arch/m68k/configs/m5208evb_defconfig:CONFIG_RAMBASE=0x40000000

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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#1270697

FromGreg Ungerer <gerg@uclinux.org>
Date2015-11-17 00:50 +0100
Message-ID<qvBH3-5vs-1@gated-at.bofh.it>
In reply to#1270103
Hi Geert,

On 16/11/15 23:05, Geert Uytterhoeven wrote:
> On Mon, Nov 16, 2015 at 1:18 PM, Greg Ungerer <gerg@uclinux.org> wrote:
>>> --- a/arch/m68k/kernel/setup_no.c
>>> +++ b/arch/m68k/kernel/setup_no.c
>>> @@ -238,11 +238,14 @@ void __init setup_arch(char **cmdline_p)
>>>          * Give all the memory to the bootmap allocator, tell it to put
>>> the
>>>          * boot mem_map at the start of memory.
>>>          */
>>> +       min_low_pfn = PFN_DOWN(memory_start);
>>> +       max_pfn = max_low_pfn = PFN_DOWN(memory_end);
>>> +
>>>         bootmap_size = init_bootmem_node(
>>>                         NODE_DATA(0),
>>> -                       memory_start >> PAGE_SHIFT, /* map goes here */
>>> -                       PAGE_OFFSET >> PAGE_SHIFT,      /* 0 on coldfire
>>> */
>>> -                       memory_end >> PAGE_SHIFT);
>>> +                       min_low_pfn,            /* map goes here */
>>> +                       PFN_DOWN(PAGE_OFFSET),  /* 0 on coldfire */
>>> +                       max_pfn);
>>>         /*
>>>          * Free the usable memory, we have to make sure we do not free
>>>          * the bootmem bitmap so we then reserve it after freeing it :-)
>>
>> Should this be changed to use init_bootmem() as per your changes
>> in patch 3 ("m68k/mm: sun3 - Add missing initialization of max_pfn and
>> {min,max}_low_pfn")? For the same reason?
> 
> No. PAGE_OFFSET = PAGE_OFFSET_RAW = CONFIG_RAMBASE.
> As the comment says, this is zero on coldfire, but not on all m68knommu
> platforms.
> 
> Upon closer look, this isn't even true on all Coldfire boards:
> 
> arch/m68k/configs/m5208evb_defconfig:CONFIG_RAMBASE=0x40000000

Yes, that comment is definitely wrong!

Regards
Greg


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