lkml.org 
[lkml]   [2003]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: no more MTRRs available ?
On Wed, 29 Jan 2003 10:51:03 -0500 (EST)
Mark Hahn <hahn@physics.mcmaster.ca> wrote:

> > > > what exactly does
> > > >
> > > > mtrr: no more MTRRs available
> > > > mtrr: no more MTRRs available
> > > >
> > > > during boot mean? What can I do against this? This comes up while
> > > > booting a system with 6GB and P-III 1.4 GHz (Serverworks chipset).
> > > > Kernel is 2.4.20.
> > >
> > > you need to look at /proc/mtrr.
> >
> > Thanks for your hint, but what does this tell me?
>
> that your bios is stupid, I think. mtrr's handle areas that are
> powers of two in size (and >= 1M, I think). the problem here is that
> the bios is trying to represent 4G of write-back ram and a 16M of
> uncachable IO area (AGP aperture, I'm guessing). the correct way
> to do this is a single 4G mtrr with an overlapping 16M one.

Ah, I see. So getting the above two messages would simply mean that there is no
table space left to add yet another two entries kernel gets from bios?

> do you have >4G ram? that would explain the latter two.

Yes, this box has 6GB.

> note that you can fairly freely add/delete mtrr's from userspace.
> as long as you do it infrequently, I don't see why there would be
> any risk or performance problem.

So the conclusion is that it does not look nice currently, but does not do any
harm (performance loss) either. I can live with that.
Thanks for your comments.

> > # cat /proc/mtrr
> > reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
> > reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
> > reg02: base=0xc0000000 (3072MB), size= 512MB: write-back, count=1
> > reg03: base=0xe0000000 (3584MB), size= 256MB: write-back, count=1
> > reg04: base=0xf0000000 (3840MB), size= 128MB: write-back, count=1
> > reg05: base=0xf7000000 (3952MB), size= 16MB: uncachable, count=1
> > reg06: base=0x100000000 (4096MB), size=4096MB: write-back, count=1
> > reg07: base=0x200000000 (8192MB), size=8192MB: write-back, count=1
--
Regards,
Stephan
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:32    [W:0.041 / U:0.388 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site