Re: Strange mtrrs in Aspire One

["J.A. Magallón" <jamagallon@ono.com>]

On Sat, 4 Oct 2008 14:54:24 -0700, "Yinghai Lu" <yinghai@kernel.org> wrote:

> On Sat, Oct 4, 2008 at 10:55 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> > On Sat, Oct 4, 2008 at 6:22 AM, J.A. Magallón <jamagallon@ono.com> wrote:
> >> On Mon, 29 Sep 2008 18:05:51 -0700, "Yinghai Lu" <yinghai@kernel.org> wrote:
> >>
> >>> On Mon, Sep 29, 2008 at 4:57 PM, J.A. Magallón <jamagallon@ono.com> wrote:
> >>> > Hi all...
> >>> >
> >>> > My aspire one is giving some strange MTRR settings with rc7-git5 (and
> >>> > prevous kernels, but that is what I run now...):
> >>> >
> >>> > one:~> cat /proc/mtrr
> >>> > reg00: base=0xfffe0000 (4095MB), size= 128KB: write-protect, count=1
> >>> > reg01: base=0xfffc0000 (4095MB), size= 128KB: uncachable, count=1
> >>>
> >>> could make mtrr_cleanup to support 128K gran_size
> >>>
> >>> > reg02: base=0x00000000 (   0MB), size= 256MB: write-back, count=1
> >>> > reg03: base=0x10000000 ( 256MB), size= 256MB: write-back, count=1
> >>> > reg04: base=0x1f800000 ( 504MB), size=   8MB: uncachable, count=1
> >>> > reg05: base=0x1f600000 ( 502MB), size=   2MB: uncachable, count=1
> >>> > reg06: base=0x1f500000 ( 501MB), size=   1MB: uncachable, count=1
> >>>
> >>> > reg07: base=0x00000000 (   0MB), size= 128KB: uncachable, count=1
> >>> ..
> >>> >  BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
> >>>
> >>> last entry is really sick...
> >>>
> >>
> >> I have applied the patches you have posted in other threads, and this
> >> give a very strange result. The mtrr cleanup did nothing, and I had to put
> >> some printk's all around.
> >
> > will have one patch to assume the [0, 1M) to be coverred by var mtrrs.
> >
> 
> please check other three patches.
> 
> [PATCH 1/3] x86: mtrr_cleanup: print out correct type
> [PATCH 2/3] x86: mtrr_cleanup: first 1M should be coverred in var mtrrs
> [PATCH 3/3] x86: mtrr_cleanup: treat WRPROT as UNCACHEABLE
> 

Thanks, will try.

> you may need to boot with "mtrr_gran_size=64k mtrr_chunk_size=64k"
> 

This makes me think about a question.
In the dual xeon box, the 'cleanup' ends with this setup:

werewolf:~> cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=1024MB: write-back, count=1
reg01: base=0x40000000 (1024MB), size= 512MB: write-back, count=1
reg02: base=0x60000000 (1536MB), size= 256MB: write-back, count=1
reg03: base=0x70000000 (1792MB), size= 128MB: write-back, count=1
reg04: base=0x78000000 (1920MB), size=  64MB: write-back, count=1
reg05: base=0x7c000000 (1984MB), size=  64MB: write-back, count=1
reg06: base=0x7ff00000 (2047MB), size=   1MB: uncachable, count=1

Ths options with 0 me loose were:

 gran_size: 64K     chunk_size: 32M     num_reg: 8      lose cover RAM: 0G
 gran_size: 64K     chunk_size: 64M     num_reg: 7      lose cover RAM: 0G
 gran_size: 64K     chunk_size: 128M    num_reg: 6      lose cover RAM: 0G
 gran_size: 64K     chunk_size: 256M    num_reg: 5      lose cover RAM: 0G
 gran_size: 64K     chunk_size: 512M    num_reg: 4      lose cover RAM: 0G
 gran_size: 64K     chunk_size: 1G  num_reg: 3      lose cover RAM: 0G
 gran_size: 64K     chunk_size: 2G  num_reg: 2      lose cover RAM: 0G
 ...
 gran_size: 128K    chunk_size: 32M     num_reg: 8      lose cover RAM: 0G
 gran_size: 128K    chunk_size: 64M     num_reg: 7      lose cover RAM: 0G
 gran_size: 128K    chunk_size: 128M    num_reg: 6      lose cover RAM: 0G
 gran_size: 128K    chunk_size: 256M    num_reg: 5      lose cover RAM: 0G
 gran_size: 128K    chunk_size: 512M    num_reg: 4      lose cover RAM: 0G
  gran_size: 128K    chunk_size: 1G  num_reg: 3      lose cover RAM: 0G
 gran_size: 128K    chunk_size: 2G  num_reg: 2      lose cover RAM: 0G
 ...
 gran_size: 256K    chunk_size: 32M     num_reg: 8      lose cover RAM: 0G
 gran_size: 256K    chunk_size: 64M     num_reg: 7      lose cover RAM: 0G
 gran_size: 256K    chunk_size: 128M    num_reg: 6      lose cover RAM: 0G
 gran_size: 256K    chunk_size: 256M    num_reg: 5      lose cover RAM: 0G
 gran_size: 256K    chunk_size: 512M    num_reg: 4      lose cover RAM: 0G
 gran_size: 256K    chunk_size: 1G  num_reg: 3      lose cover RAM: 0G
 gran_size: 256K    chunk_size: 2G  num_reg: 2      lose cover RAM: 0G
...
 gran_size: 512K    chunk_size: 32M     num_reg: 8      lose cover RAM: 0G
 gran_size: 512K    chunk_size: 64M     num_reg: 7      lose cover RAM: 0G
 gran_size: 512K    chunk_size: 128M    num_reg: 6      lose cover RAM: 0G
 gran_size: 512K    chunk_size: 256M    num_reg: 5      lose cover RAM: 0G
 gran_size: 512K    chunk_size: 512M    num_reg: 4      lose cover RAM: 0G
 gran_size: 512K    chunk_size: 1G  num_reg: 3      lose cover RAM: 0G
 gran_size: 512K    chunk_size: 2G  num_reg: 2      lose cover RAM: 0G
...
 gran_size: 1M  chunk_size: 32M     num_reg: 8      lose cover RAM: 0G
 gran_size: 1M  chunk_size: 64M     num_reg: 7      lose cover RAM: 0G
 gran_size: 1M  chunk_size: 128M    num_reg: 6      lose cover RAM: 0G
 gran_size: 1M  chunk_size: 256M    num_reg: 5      lose cover RAM: 0G
 gran_size: 1M  chunk_size: 512M    num_reg: 4      lose cover RAM: 0G
 gran_size: 1M  chunk_size: 1G  num_reg: 3      lose cover RAM: 0G
 gran_size: 1M  chunk_size: 2G  num_reg: 2      lose cover RAM: 0G
 ...
Found optimal setting for mtrr clean up
gran_size: 64K  chunk_size: 64M     num_reg: 7      lose RAM: 0G

Why did it choose that using 7 registers ? Should'n it get that with the
smallest number of used registers, and from those the bigger gran_size ?
If the purpose is to leave space for more mtrrs (from X or other...).
In short, what is the purpose of having this:

reg00: base=0x00000000 (   0MB), size=1024MB: write-back, count=1
reg01: base=0x40000000 (1024MB), size= 512MB: write-back, count=1
reg02: base=0x60000000 (1536MB), size= 256MB: write-back, count=1
reg03: base=0x70000000 (1792MB), size= 128MB: write-back, count=1
reg04: base=0x78000000 (1920MB), size=  64MB: write-back, count=1
reg05: base=0x7c000000 (1984MB), size=  64MB: write-back, count=1
reg06: base=0x7ff00000 (2047MB), size=   1MB: uncachable, count=1

instead of this:

reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
reg01: base=0x7ff00000 (2047MB), size=   1MB: uncachable, count=1

If both set a hole, not a set of valid zones without holes ?

??

-- 
J.A. Magallon <jamagallon()ono!com>     \               Software is like sex:
                                         \         It's better when it's free
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