[RFC PATCH] crashdump/x86: Add option to get crash kernel region size

[Daniel Kiper]

On Mon, Nov 30, 2015 at 08:55:32AM +0900, Simon Horman wrote:
> On Sat, Nov 28, 2015 at 09:14:04PM +0100, Daniel Kiper wrote:
> > Crash kernel region size is available via sysfs on Linux running on
> > bare metal. However, this does not work when Linux runs as Xen dom0.
> > In this case Xen crash kernel region size should be established using
> > __HYPERVISOR_kexec_op hypercall (Linux kernel kexec functionality does
> > not make a lot of sense in Xen dom0). Sadly hypercalls are not easily
> > accessible using shell scripts or something like that. Potentially we
> > can check "xl dmesg" output for crashkernel option but this is not nice.
> > So, let's add this functionality, for Linux running on bare metal and
> > as Xen dom0, to kexec-tools. This way kdump scripts may establish crash
> > kernel region size in one way regardless of platform. All burden of
> > platform detection lies on kexec-tools.
> >
> > Figure (and unit) displayed by this new kexec-tools functionality is
> > the same as one taken from /sys/kernel/kexec_crash_size.
> >
> > This functionality is available on x86 platform only. If idea is acceptable
> > then I can prepare patches for other platforms (if it is possible and make
> > sense) and repost them as fully flagged patch series.
> >
> > Signed-off-by: Daniel Kiper <daniel.kiper at oracle.com>
>
> Thanks, applied.

Thanks a lot. However, this patch itself breaks build on other platforms.
That is why I posted it as a RFC. To fix this I can post similar patches
for other platforms (this will happen probably tomorrow or on Wednesday
but no later than by the end of this week). Or you can revert this patch
and than I repost it as a part of fully functional patch series.

Daniel