Re: [PATCH]IA64: do not include uncached memory to vmcore

Re: [PATCH]IA64: do not include uncached memory to vmcore

[Simon Horman]

On Fri, Sep 12, 2008 at 01:10:34PM -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 may MCA when it tries to save the vmcore to a disk.
> A normal "cached" access can cause MCAs.
> 
> Since kexec assembled memory ranges with memory tagged as "System RAM",
> the uncached memory will be excluded if it is labeled differently.
> 
> Simon, since only IA64 will create "Uncached RAM" label, i do not
> make changes to other arch.
> 
> Our HP machine in the lab is dead. I am sorry that i can not test
> against other IA64 systems (than SGI's). Feedback is very much
> appreciated.
> 
> The corresponding kernel patch is needed to test this kexec patch:
> http://marc.info/?l=linux-ia64&m\x122122791230130&w=2
> This patch without the kernel patch will have no effect and do no
> harm.

Hi Jay,

both of these patches seem reasonable to me, especially from a kexec point
of view. I will try and test them on an HP RX2620 and Intel Tiger 4 and
get back to you shortly.

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

Re: [PATCH]IA64: do not include uncached memory to vmcore

[Simon Horman]

On Sat, Sep 13, 2008 at 09:35:02AM +1000, Simon Horman wrote:
> On Fri, Sep 12, 2008 at 01:10:34PM -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 may MCA when it tries to save the vmcore to a disk.
> > A normal "cached" access can cause MCAs.
> > 
> > Since kexec assembled memory ranges with memory tagged as "System RAM",
> > the uncached memory will be excluded if it is labeled differently.
> > 
> > Simon, since only IA64 will create "Uncached RAM" label, i do not
> > make changes to other arch.
> > 
> > Our HP machine in the lab is dead. I am sorry that i can not test
> > against other IA64 systems (than SGI's). Feedback is very much
> > appreciated.
> > 
> > The corresponding kernel patch is needed to test this kexec patch:
> > http://marc.info/?l=linux-ia64&m\x122122791230130&w=2
> > This patch without the kernel patch will have no effect and do no
> > harm.
> 
> Hi Jay,
> 
> both of these patches seem reasonable to me, especially from a kexec point
> of view. I will try and test them on an HP RX2620 and Intel Tiger 4 and
> get back to you shortly.

Hi Jay, Hi All,

As "[IA64] kexec fails on systems with blocks of uncached memory" has
been applied to the kernel by Tony and pulled by Linus, I have
applied this kexec-tools portion of the patch.

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