Re: [PATCH] [arch-x86] Allow SRAT integrity check to be skipped

Ingo Molnar
2010-09-02T06:57:44Z

* Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com> wrote:

> On certain BIOSes, SRAT enumeration isn't exported correctly. This
> leads to NUMA node enumeration failure, and causes the kernel to fall
> back onto a single node treated as flat memory. This can happen on
> large, multi-socket systems (4 or more sockets), and becomes
> problematic for performance.
>
> This patch adds a boot parameter to allow a kernel to be booted with
> the option to skip the SRAT check. There are BIOSes in production
> that have these failures, so this will allow people in the field to
> work around these BIOS issues.

> + sratbypassbios
> + If specified, will skip an SRAT check for PXM coverage
> + from BIOS enumeration. Only to be used on systems with
> + buggy BIOSes that munge the SRAT enumeration.

This isnt a particularly useful solution to users of said systems - they
have to figure out that this option exists, and then they have to enter
this option on the boot line.

A better solution would be to match these systems using DMI filters -
_and_ to also have the boot time option to cover the case where a new
system comes out with such a breakage. (or there's some system not yet
mapped)

Ingo