[Xen-devel] KEXEC: allocate crash note buffers at boot time v5

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Here is v5.

I have tested quite carefully the impact of changing the error
conditions in kexec_get_cpu().  dom0 is happy to accept ERANGE as well
as EINVAL, and ERANGE is a more sensible response.  Moreover, this new
scheme (ignoring for a moment ENOMEM) allows for all nr_cpu_ids to give
note ranges to dom0 whether they are up or not at the moment.   It is
better to have more notes provided with some of them potentially not
filled in, than to miss a crashed CPU register state because it was
offline when the crash kernel was loaded.

All this testing has been done via backport to 4.1.2.  Minimal changes
were necessary, such as the lack of xzalloc_array() and NR_CPUS instead
of nr_cpu_ids, but it was otherwise functionally identical.

I am not sure whether to recomend this for backport into 4.1-testing or
not.  It does make the crashkernel more likely to get crash notes,
although in reality, it was only special circumstances which caused
problems.  If you consider it worth backporting, I can provide my
already-backported patch.

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com

Attachment: KEXEC-setup-crash-notes-during-boot.patch
Description: Text Data

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