[PATCH]IA64: assign a distinguishable label to uncached memory in /proc/iomem

[Simon Horman]

On Thu, Sep 11, 2008 at 04:00:08PM -0700, Jay Lan wrote:
> Currently a memory segment in memory map with attribute of EFI_MEMORY_UC
> is denoted as "System RAM" in /proc/iomem, while memory of attribute
> (EFI_MEMORY_WB|EFI_MEMORY_UC) is also labeled the same.
> 
> The kexec utility then includes uncached memory as part of vmcore. The
> kdump kernel MCA'ed when it tries to save the vmcore to a disk. A normal
> "cached" access may cause MCAs.
> 
> This patch would label memory with attribute of EFI_MEMORY_UC only as
> "Uncached RAM" so that kexec would know not to include it in the vmcore.
> I will submit a separate kexec-tools patch to the kexec list.
> 
> Signed-off-by: Jay Lan <jlan at sgi.com>

Hi Jay,

I've taken a look on an RX2620, Tiger2 and Tiger4 and none of these
machines have EFI memory regions that are covered by this new check. That
is, any regions with the EFI_MEMORY_UC bit set in the attribute either also
have other attibute bits set, or are of a type not covered by this.

I strongly suspect that this is not a problem, but I wanted to bring it to
your attention anyway. I can provide more detailed EFI information from any
or all of these machines if you need it.

With regards to the kexec-tools portion of this patch, it looks fine to me
and I don't think there will be any problem in merging it if/when the
kernel portion is accepted.

-- 
Simon Horman
  VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
  H: www.vergenet.net/~horms/             W: www.valinux.co.jp/en