mtrr question

mtrr question

[Nick Warne]

Hello everybody,

Dumb question here.

I have an Athlon-thunderbird (1.2Ghz) on kernel 2.4.31 with mttr configured 
and a nVidia Geforce4.  /proc/mtrr is empty.

Does/is setting up mtrr per the old 1999 Docs/mtrr.txt still relevant 
nowadays?  I can't seem to find a definitive answer using Google.

TIA,

Nick
-- 
"When you're chewing on life's gristle,
Don't grumble, Give a whistle..."

Re: mtrr question

[Dave Jones]

On Wed, Jun 08, 2005 at 07:17:09PM +0100, Nick Warne wrote:
 > Hello everybody,
 > 
 > Dumb question here.
 > 
 > I have an Athlon-thunderbird (1.2Ghz) on kernel 2.4.31 with mttr configured 
 > and a nVidia Geforce4.  /proc/mtrr is empty.

That's odd. you should at least have write-back entries for your system memory.
(Usually set up by the system BIOS)

 > Does/is setting up mtrr per the old 1999 Docs/mtrr.txt still relevant 
 > nowadays?  I can't seem to find a definitive answer using Google.

Yes, though the X driver should set them up itself on startup.

		Dave

Re: mtrr question

[Nick Warne]

On Wednesday 08 June 2005 20:23, Dave Jones wrote:

> That's odd. you should at least have write-back entries for your system
> memory. (Usually set up by the system BIOS)
>
>  > Does/is setting up mtrr per the old 1999 Docs/mtrr.txt still relevant
>  > nowadays?  I can't seem to find a definitive answer using Google.
>
> Yes, though the X driver should set them up itself on startup.

Yes, I read that, and did wonder...

Ummm.  I see from boot logs that mtrr isn't detected like it is on my other 
(Dell) boxes.

This looks like my BIOS settings are wonky then.  What would it be 'called' to 
enable/disable mtrr on an AGP slot?

Thanks,

Nick
-- 
"When you're chewing on life's gristle,
Don't grumble, Give a whistle..."

Re: mtrr question

[Dave Jones]

On Wed, Jun 08, 2005 at 08:31:59PM +0100, Nick Warne wrote:

 > Ummm.  I see from boot logs that mtrr isn't detected like it is on my other 
 > (Dell) boxes.

Hmm, that sounds like it isn't compiled in. Though that doesn't make
sense why you still have a /proc/mtrr
 
 > This looks like my BIOS settings are wonky then.  What would it be 'called' to 
 > enable/disable mtrr on an AGP slot?

Its typically not a setting, just something the BIOS does as part
of its CPU initialisation.  I've never encountered a BIOS that had
it configurable.

		Dave
 

Re: mtrr question

[Nick Warne]

On Wednesday 08 June 2005 20:35, Dave Jones wrote:
> On Wed, Jun 08, 2005 at 08:31:59PM +0100, Nick Warne wrote:
>  > Ummm.  I see from boot logs that mtrr isn't detected like it is on my
>  > other (Dell) boxes.
>
> Hmm, that sounds like it isn't compiled in. Though that doesn't make
> sense why you still have a /proc/mtrr

OK, ignore my previous comment (too many Linux boxes here).  The one I am 
investigating is my main Desktop, and dmesg confirms.  mtrr is detected as 
'Intel' which is right as per the Docs (even though I have an AMD).

I also forgot to say I use the nVidia agp module (works better for me in 
Quake2 for some reason)... but searching their docs doesn't even mention 
mtrr.

Could it be that?  If so, I am wasting you guys time.

Thanks,

Nick
-- 
"When you're chewing on life's gristle,
Don't grumble, Give a whistle..."

Re: mtrr question

[Dave Jones]

On Wed, Jun 08, 2005 at 08:47:13PM +0100, Nick Warne wrote:
 > On Wednesday 08 June 2005 20:35, Dave Jones wrote:
 > > On Wed, Jun 08, 2005 at 08:31:59PM +0100, Nick Warne wrote:
 > >  > Ummm.  I see from boot logs that mtrr isn't detected like it is on my
 > >  > other (Dell) boxes.
 > >
 > > Hmm, that sounds like it isn't compiled in. Though that doesn't make
 > > sense why you still have a /proc/mtrr
 > 
 > OK, ignore my previous comment (too many Linux boxes here).  The one I am 
 > investigating is my main Desktop, and dmesg confirms.  mtrr is detected as 
 > 'Intel' which is right as per the Docs (even though I have an AMD).
 > 
 > I also forgot to say I use the nVidia agp module (works better for me in 
 > Quake2 for some reason)... but searching their docs doesn't even mention 
 > mtrr.
 > 
 > Could it be that?  If so, I am wasting you guys time.

Maybe. I don't use non-free drivers, so I have no idea
what nvidia are/aren't doing in their driver.

I'd suggest trying the nvidia forums.

		Dave

Re: mtrr question

[Nick Warne]

On Wednesday 08 June 2005 20:53, Dave Jones wrote:
> Maybe. I don't use non-free drivers, so I have no idea
> what nvidia are/aren't doing in their driver.
>
> I'd suggest trying the nvidia forums.

No need ;-).  You helped me pinpoint it... I went for it and ran manually:

bash-2.05b# echo "base=0xD0000000 size=0x4000000 type=write-combining" 
>| /proc/mtrr

bash-2.05b# cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=1024MB: write-back, count=1
reg01: base=0x40000000 (1024MB), size= 256MB: write-back, count=1
reg02: base=0xd0000000 (3328MB), size=  64MB: write-combining, count=1
reg05: base=0xc0000000 (3072MB), size= 256MB: write-combining, count=1

Thanks for help Dave... very much appreciated.  I will look back and use Linux 
kernel module next build - I want things be nice and free too.

Nick
-- 
"When you're chewing on life's gristle,
Don't grumble, Give a whistle..."

Re: mtrr question

[Nick Warne]

On Wednesday 08 June 2005 20:53, Dave Jones wrote:

>  > I also forgot to say I use the nVidia agp module (works better for me in
>  > Quake2 for some reason)... but searching their docs doesn't even mention
>  > mtrr.
>  >
>  > Could it be that?  If so, I am wasting you guys time.
>
> Maybe. I don't use non-free drivers, so I have no idea
> what nvidia are/aren't doing in their driver.

This is confirmed it is a nvidia thing.  Tonight I have just upgraded 
(updated?) from 2.4.31 to 2.6.11.12 kernel (whooo), and used agpart - I now 
have /proc/mtrr values as expected from boot.

Quake2 works great too :-)

Nick
-- 
"When you're chewing on life's gristle,
Don't grumble, Give a whistle..."