Re: [PATCH 2/2] x86: mtrr_cleanup try gran_size to less than 1M

Yinghai Lu
2008-10-02T23:45:59Z

On Thu, Oct 2, 2008 at 4:20 PM, J.A. Magallón <jamagallon@ono.com> wrote:
> On Thu, 2 Oct 2008 15:39:34 -0700, "Yinghai Lu" <yinghai@kernel.org> wrote:
>
> Oops, sorry, this is without cleanup. This is a distro kernel and is built
> but not enable by deafult. As it is rc7, I will use 'enble_mtrr_cleanup' ;):
>
> cicely:~# cat /proc/mtrr
> reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
> reg01: base=0x100000000 (4096MB), size=1024MB: write-back, count=1
> reg02: base=0x140000000 (5120MB), size= 512MB: write-back, count=1
> reg03: base=0x160000000 (5632MB), size= 256MB: write-back, count=1
>
> I have lost 2Gb ?

that is memhole

>
> cicely:~# free
> total used free shared buffers cached
> Mem: 3755568 182348 3573220 0 14024 72716
> -/+ buffers/cache: 95608 3659960
>
> I can't easily try your patch, this is a distro kernel.
> I will get the src.rpm...

just pull tip/master, and use your config from /boot/config....

>
> Ahhhhh....
>
> This is a dual opteron board. dmidecode says:
>
> Handle 0x0026, DMI type 16, 15 bytes
> Physical Memory Array
> Location: System Board Or Motherboard
> Use: System Memory
> Error Correction Type: Single-bit ECC
> Maximum Capacity: 8 GB
> Error Information Handle: Not Provided
> Number Of Devices: 8
>
> So it maps one Opteron memory in first 4Gb and the other on the second 4Gb.
> So I should have 2Gb@0 and 2Gb@4Gb.
> What I don't know is why the bios eats up 256Mb.

check if you enable memhole remapping in BIOS.

YH