Re: [PATCH 01/11] resource: Add System RAM resource type

From	Toshi Kani <toshi.kani@hpe.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 01/11] resource: Add System RAM resource type
Date	2015-12-16 16:50 +0100
Message-ID	<qGmuZ-3Cs-9@gated-at.bofh.it> (permalink)
References	<qFKSJ-4sB-19@gated-at.bofh.it> <qGjns-1I6-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, 2015-12-16 at 13:26 +0100, Borislav Petkov wrote:
> On Mon, Dec 14, 2015 at 04:37:16PM -0700, Toshi Kani wrote:
> > I/O resource type, IORESOURCE_MEM, is used for all types of
> > memory-mapped ranges, ex. System RAM, System ROM, Video RAM,
> > Persistent Memory, PCI Bus, PCI MMCONFIG, ACPI Tables, IOAPIC,
> > reserved, and so on.  This requires walk_system_ram_range(),
> > walk_system_ram_res(), and region_intersects() to use strcmp()
> > against string "System RAM" to search System RAM ranges in the
> > iomem table, which is inefficient.  __ioremap_caller() and
> > reserve_memtype() on x86, for instance, call walk_system_ram_range()
> > for every request to check if a given range is in System RAM ranges.
> > 
> > However, adding a new I/O resource type for System RAM is not
> > a viable option [1].
> 
> I think you should explain here why it isn't a viable option instead of
> quoting some flaky reference which might or might not be there in the
> future.

Agreed.  I will include summary of the descriptions here.

> > Instead, this patch adds a new modifier
> > flag IORESOURCE_SYSRAM to IORESOURCE_MEM, which introduces an
> > extended I/O resource type, IORESOURCE_SYSTEM_RAM [2].
> > 
> > To keep the code 'if (resource_type(r) == IORESOURCE_MEM)' to
> > work continuously for System RAM, resource_ext_type() is added
> > for extracting extended type bit(s).
> > 
> > Cc: Linus Torvalds <torvalds@linux-foundation.org>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Borislav Petkov <bp@alien8.de>
> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Cc: Dan Williams <dan.j.williams@intel.com>
> > Reference[1]: https://lkml.org/lkml/2015/12/3/540
> > Reference[2]: https://lkml.org/lkml/2015/12/3/582
> 
> References should look something like this:
> 
> Link: http://lkml.kernel.org/r/<Message-ID>;

I see.  I will update per the format.

> > Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
> > ---
> >  include/linux/ioport.h |   11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> > index 24bea08..4b65d94 100644
> > --- a/include/linux/ioport.h
> > +++ b/include/linux/ioport.h
> > @@ -49,12 +49,19 @@ struct resource {
> >  #define IORESOURCE_WINDOW	0x00200000	/* forwarded by
> > bridge */
> >  #define IORESOURCE_MUXED	0x00400000	/* Resource is
> > software muxed */
> >  
> > +#define IORESOURCE_EXT_TYPE_BITS 0x01000000	/* Resource
> > extended types */
> 
> Should this be 0x07000000 so that we make all there bits belong to the
> extended types? Are we going to need so many?

Besides "System RAM", which is commonly searched by multiple callers, we
only have a few other uncommon cases:
 - crash.c searches for "GART", "ACPI Tables", and "ACPI Non-volatile
Storage".
 - kexec_file.c searches for "Crash kernel".
 - einj.c will search for "Persistent Memory".

This is because drivers typically know their ranges without searching
through the resource table.  So, it does not seem that we need to
preallocate the bits at this point.

Thanks,
-Toshi
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Thread

[PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:40 +0100
  [PATCH 08/11] memremap: Change region_intersects() to use System RAM type Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:40 +0100
  [PATCH 06/11] kexec: Set IORESOURCE_SYSTEM_RAM to System RAM Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:40 +0100
  [PATCH 10/11] arm/samsung: Change s3c_pm_run_res() to use System RAM type Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:40 +0100
    Re: [PATCH 10/11] arm/samsung: Change s3c_pm_run_res() to use System  RAM type Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-12-15 01:30 +0100
  [PATCH 07/11] memory-hotplug: Set IORESOURCE_SYSTEM_RAM to System RAM Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:40 +0100
  [PATCH 04/11] arch: Set IORESOURCE_SYSTEM_RAM to System RAM Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:40 +0100
  [PATCH 09/11] resource: Change walk_system_ram to use System RAM type Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:40 +0100
  [PATCH 05/11] xen: Set IORESOURCE_SYSTEM_RAM to System RAM Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:50 +0100
  [PATCH 03/11] x86/e820: Set IORESOURCE_SYSTEM_RAM to System RAM Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 00:50 +0100
  Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-16 13:30 +0100
    Re: [PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-16 16:50 +0100
      Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-16 16:50 +0100
        Re: [PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-16 17:40 +0100
          Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-16 18:50 +0100
            Re: [PATCH 01/11] resource: Add System RAM resource type Dan Williams <dan.j.williams@intel.com> - 2015-12-16 19:00 +0100
              Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-16 19:20 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Dan Williams <dan.j.williams@intel.com> - 2015-12-16 20:00 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-16 20:20 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-16 23:00 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-22 12:40 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-22 21:10 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-23 15:30 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-24 03:30 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-24 18:10 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Borislav Petkov <bp@alien8.de> - 2015-12-24 21:00 +0100
                Re: [PATCH 01/11] resource: Add System RAM resource type Toshi Kani <toshi.kani@hpe.com> - 2015-12-24 22:40 +0100

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