[gentoo-user] [OT?] MTRR and PAT

[gentoo-user] [OT?] MTRR and PAT

[pk]

Hi,

(Sorry if this is off-topic but I really don't know where to turn to...)

Anyone with experience/knowledge about MTRR/PAT and who can tell me 
where to find information about these things so that I might see if 
there's a problem or not? I've tried google but in this case they're not 
my friend... :-(

The MTRR of one of my machines look like this:
reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
reg02: base=0xbff00000 (3071MB), size=   1MB: uncachable, count=1
reg03: base=0x100000000 (4096MB), size=1024MB: write-back, count=1

The gfx card is a (pcie) Radeon HD3850 and the base address for the 
framebuffer is 0xd0000000 (64-bit, prefetchable) [size=256M]. It also 
has (what I believe is) registers at 0xf1000000 (64-bit, 
non-prefetchable) [size=64K].

One of my other machines get's warnings about

All the relevant info that comes up when I use google relates to AGP but 
I use PCIE, so is it still relevant? Also, are there other devices 
besides the graphics card that would benefit from having a correct MTRR 
setting?

TIA,

Peter K
-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] [OT?] MTRR and PAT

[Andrey Falko]

On Sun, May 11, 2008 at 3:49 AM, pk <peterk2@coolmail.se> wrote:
> Hi,
>
> (Sorry if this is off-topic but I really don't know where to turn to...)
>
> Anyone with experience/knowledge about MTRR/PAT and who can tell me where to
> find information about these things so that I might see if there's a problem
> or not? I've tried google but in this case they're not my friend... :-(
>
> The MTRR of one of my machines look like this:
> reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
> reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
> reg02: base=0xbff00000 (3071MB), size=   1MB: uncachable, count=1
> reg03: base=0x100000000 (4096MB), size=1024MB: write-back, count=1
>
> The gfx card is a (pcie) Radeon HD3850 and the base address for the
> framebuffer is 0xd0000000 (64-bit, prefetchable) [size=256M]. It also has
> (what I believe is) registers at 0xf1000000 (64-bit, non-prefetchable)
> [size=64K].
>
> One of my other machines get's warnings about
>
> All the relevant info that comes up when I use google relates to AGP but I
> use PCIE, so is it still relevant? Also, are there other devices besides the
> graphics card that would benefit from having a correct MTRR setting?
>
> TIA,
>
> Peter K

What kernel version are you using? How are you compiling your kernel
(i.e. with genkernel or manually)? If you are manually compiling your
kernel, can you send us your .config file?
-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] [OT?] MTRR and PAT

[pk]

[-- Attachment #1: Type: text/plain, Size: 377 bytes --]

Andrey Falko wrote:
> On Sun, May 11, 2008 at 3:49 AM, pk <peterk2@coolmail.se> wrote:

> What kernel version are you using? How are you compiling your kernel
> (i.e. with genkernel or manually)? If you are manually compiling your
> kernel, can you send us your .config file?

gentoo-sources-2.6.23-r9, manually compiled.

Config file attached.

Thanks!

Best regards

Peter K

[-- Attachment #2: config-2.6.23-r9.gz --]
[-- Type: application/gzip, Size: 11091 bytes --]

Re: [gentoo-user] [OT?] MTRR and PAT

[Andrey Falko]

On Sun, May 11, 2008 at 4:15 AM, pk <peterk2@coolmail.se> wrote:
> Andrey Falko wrote:
>>
>> On Sun, May 11, 2008 at 3:49 AM, pk <peterk2@coolmail.se> wrote:
>
>> What kernel version are you using? How are you compiling your kernel
>> (i.e. with genkernel or manually)? If you are manually compiling your
>> kernel, can you send us your .config file?
>
> gentoo-sources-2.6.23-r9, manually compiled.
>
Try 2.6.24, I'm afraid that your video might be too new for 2.6.23.
> Config file attached.
>

Here are my comments your config:

-In General Setup: Try choosing SLAB allocator.
-Your Bus Options look good.
-I'm 80% sure that you are not supposed to have /dev/agpgart enabled
since you are using PCI-Express....I have a PCI-Express system and I
have it disabled. Actually, I don't have anything enabled under
"Graphic Support". Since you are using Radeon, I think you might need
to enable Direct Rendering Manager, then choose Radeon.


> Thanks!
>
> Best regards
>
> Peter K
>
-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] [OT?] MTRR and PAT

[pk]

Andrey Falko wrote:
> Try 2.6.24, I'm afraid that your video might be too new for 2.6.23.

Well, I think you have misunderstood my question(s). I may have been 
unclear as to what I would like to achieve... My goal is to see if my 
MTRR settings are ok or not; well, even better would be if I could 
understand the settings so that I can make a judgement myself if it's ok 
or not.

The video (X) works fine as it is (not counting the occasional artifact 
in 3D games).

> Here are my comments your config:
> 
> -In General Setup: Try choosing SLAB allocator.

Well, I tried to live on the "edge" a little, trying it out... ;-)

> -Your Bus Options look good.
> -I'm 80% sure that you are not supposed to have /dev/agpgart enabled
> since you are using PCI-Express....I have a PCI-Express system and I
> have it disabled. Actually, I don't have anything enabled under
> "Graphic Support". Since you are using Radeon, I think you might need
> to enable Direct Rendering Manager, then choose Radeon.

I run fglrx (AMD/Atis binary blob) and the ebuild complains if I don't 
have certain options set. This may have changed but I've used the same 
config for a while now (since around 2.6.13-14) on older systems (with 
AGP). I'm planning to migrate to radeonhd (or maybe the r300) driver 
when it has 3D support and has stabilised somewhat.

I think I've found some more info on what I'm after:
http://www.amd.com/gb-uk/Processors/TechnicalResources/0,,30_182_739_7044,00.html 

(the system programming manual).

Thanks for your time, Andrey!

Best regards

Peter K
-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] [OT?] MTRR and PAT

[Andrey Falko]

On Mon, May 12, 2008 at 2:30 PM, pk <peterk2@coolmail.se> wrote:
> Andrey Falko wrote:
>>
>> Try 2.6.24, I'm afraid that your video might be too new for 2.6.23.
>
> Well, I think you have misunderstood my question(s). I may have been unclear
> as to what I would like to achieve... My goal is to see if my MTRR settings
> are ok or not; well, even better would be if I could understand the settings
> so that I can make a judgement myself if it's ok or not.
>
> The video (X) works fine as it is (not counting the occasional artifact in
> 3D games).

Ahh I see. I don't know much about MTRR...all I know is that you can
adjust them via grub:
http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=10
. You probably read this already:
http://en.wikipedia.org/wiki/Memory_Type_Range_Registers

>
>> Here are my comments your config:
>>
>> -In General Setup: Try choosing SLAB allocator.
>
> Well, I tried to live on the "edge" a little, trying it out... ;-)
>
>> -Your Bus Options look good.
>> -I'm 80% sure that you are not supposed to have /dev/agpgart enabled
>> since you are using PCI-Express....I have a PCI-Express system and I
>> have it disabled. Actually, I don't have anything enabled under
>> "Graphic Support". Since you are using Radeon, I think you might need
>> to enable Direct Rendering Manager, then choose Radeon.
>
> I run fglrx (AMD/Atis binary blob) and the ebuild complains if I don't have
> certain options set. This may have changed but I've used the same config for
> a while now (since around 2.6.13-14) on older systems (with AGP). I'm
> planning to migrate to radeonhd (or maybe the r300) driver when it has 3D
> support and has stabilised somewhat.
>
Yeh, I have Nvidia cards, so I guess ATI is different.
> I think I've found some more info on what I'm after:
> http://www.amd.com/gb-uk/Processors/TechnicalResources/0,,30_182_739_7044,00.html
> (the system programming manual).
>
> Thanks for your time, Andrey!
Your welcome :).
>
> Best regards
>
> Peter K
> --
> gentoo-user@lists.gentoo.org mailing list
>
>
-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] [OT?] MTRR and PAT

[pk]

Andrey Falko wrote:

> Ahh I see. I don't know much about MTRR...all I know is that you can
> adjust them via grub:
> http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=10

Hmm... I missed that one. Thanks.

My grub kernel command line (which I haven't given much thought to since 
it's inception many years ago):
root=/dev/sda2 vga=804 video=vesafb:1280x1024-32@85,mtrr:3,ywrap

This should tell vesafb to set MTRR to use write-combining (for which 
memory region, I don't know), but it doesn't work for me, for some 
reason. All of my mem (under X) is set to write-back with the exception 
of 1Mb set to uncacheable. My other computer has even stranger settings 
and the kernel log complains about MTRR settings not correctly setup (it 
states that the BIOS probably doesn't init's both cores).

> . You probably read this already:
> http://en.wikipedia.org/wiki/Memory_Type_Range_Registers

Yep. Here's a few more if you (or anyone else) find this interesting:
http://en.wikipedia.org/wiki/Write-combining
http://en.wikipedia.org/wiki/Cache

Basically the MTRR (and PAT) determines how the processor (and it's 
cache(s)) accesses the memory regions (in the MTRR). Xorg supposedly 
should set up the MTRR when it starts.

> Yeh, I have Nvidia cards, so I guess ATI is different.

Perhaps.

Thanks again! It's always good to weather one's thoughts on a subject...

This just got me thinking. I'll investigate what the MTRR settings look 
like before the display manager starts...

Best regards

Peter K
-- 
gentoo-user@lists.gentoo.org mailing list