* Re: [kernel-reviewers] a small code review (2414483) Automated g4 rollback of changelist 2396062.
2006-04-26 17:36 ` [kernel-reviewers] a small code review (2414483) Automated g4 rollback of changelist 2396062 Martin Bligh
@ 2006-04-26 17:43 ` Tim Hockin
2006-04-26 18:24 ` Andi Kleen
1 sibling, 0 replies; 3+ messages in thread
From: Tim Hockin @ 2006-04-26 17:43 UTC (permalink / raw)
To: Martin Bligh; +Cc: Ken Harrenstien, linux-kernel
On Wed, Apr 26, 2006 at 10:36:54AM -0700, Martin Bligh wrote:
> Tim Hockin wrote:
> >On Wed, Apr 26, 2006 at 10:12:14AM -0700, Ken Harrenstien wrote:
> >
> >>That doesn't work because IIRC it only reports the amount of memory
> >>the kernel has been told (eg via "mem=") to manage in a certain sense,
> >>not how much is actually physically available.
> >>
> >>The I2 netboot kernel would really REALLY like some exported /proc
> >>values that accurately report physical memory (if nothing else, the
> >>number of DIMMs and their sizes). It has to figure this out in order
> >>to install the proper kernel with proper LILO command-line args.
> >
> >
> >The kernel can't really know how much memory is in the system without
> >getting chipset-specific.
> >
> >MTRR is a good way to hazard a guess, and will probably be right, but as
> >you indicated, BIOS vendors have historically been REALLY bad about
> >MTRRs. Better now, but bad a few years ago.
> >
> >SMBIOS (on our boards) *does* accurately report the number of DIMMS and
> >their sizes (and more!). But it only works on Google BIOS.
>
> Are you saying our e820 maps and srat tables are wrong? that's a little
> worrying ...
e820 is fine, except there's not a good kernel interface to it. Parsing
dmesg is *always* a last resort.
We don;t currently have SRAT. :)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [kernel-reviewers] a small code review (2414483) Automated g4 rollback of changelist 2396062.
2006-04-26 17:36 ` [kernel-reviewers] a small code review (2414483) Automated g4 rollback of changelist 2396062 Martin Bligh
2006-04-26 17:43 ` Tim Hockin
@ 2006-04-26 18:24 ` Andi Kleen
1 sibling, 0 replies; 3+ messages in thread
From: Andi Kleen @ 2006-04-26 18:24 UTC (permalink / raw)
To: Martin Bligh; +Cc: Ken Harrenstien, linux-kernel
Martin Bligh <mbligh@google.com> writes:
> Tim Hockin wrote:
> > On Wed, Apr 26, 2006 at 10:12:14AM -0700, Ken Harrenstien wrote:
> >
> >>That doesn't work because IIRC it only reports the amount of memory
> >>the kernel has been told (eg via "mem=") to manage in a certain sense,
> >>not how much is actually physically available.
> >>
> >>The I2 netboot kernel would really REALLY like some exported /proc
> >>values that accurately report physical memory (if nothing else, the
> >>number of DIMMs and their sizes). It has to figure this out in order
> >>to install the proper kernel with proper LILO command-line args.
> > The kernel can't really know how much memory is in the system without
> > getting chipset-specific.
> > MTRR is a good way to hazard a guess, and will probably be right,
> > but as
> > you indicated, BIOS vendors have historically been REALLY bad about
> > MTRRs. Better now, but bad a few years ago.
> > SMBIOS (on our boards) *does* accurately report the number of DIMMS
> > and
> > their sizes (and more!). But it only works on Google BIOS.
Actually quite a lot of SMBIOS report DIMMs more or less correct.
It works even on my laptop.
I implemented support for it in the latest mcelog (--dmi). Not all
and a few big names screw it up (in particular the mappings from
address range to interleave set). But overall it looks surprisingly
good so far.
-Andi
^ permalink raw reply [flat|nested] 3+ messages in thread