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

[Simon Horman]

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.