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Re: [Xen-devel] [PATCHv10 0/9] Xen: extend kexec hypercall for use with pv-ops kernels

On 11/08/13 09:01, Andrew Cooper wrote:
On 08/11/13 13:19, Jan Beulich wrote:
On 08.11.13 at 14:13, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:

Sorry, forgot to CC you on this series.

Can we have your opinion on whether this kexec series can be merged?
And if not, what further work and/or testing is required?
Just to clarify - unless I missed something, there was still no
review of this from Daniel or someone else known to be
familiar with the subject. If Keir gave his ack, formally this
could go in, but I wouldn't feel too well with that (the more
that apart from not having reviewed it, Daniel seems to also
continue to have problems with it).
If I am following this correctly, Jan is testing this by running xen under QEMU. All my testing has been on bare metal.
Can I have myself deemed to be familiar with the subject as far as this
is concerned?

A noticeable quantity of my contributions to Xen have been in the kexec
/ crash areas, and I am the author of the xen-crashdump-analyser.

I do realise that I certainly not impartial as far as this series is
concerned, being a co-developer.

Davids statement of "the current implementation is so broken[1] and
useless[2] that..." is completely accurate.  It is frankly a miracle
that the current code ever worked at all (and from XenServers point of
view, failed far more often than it worked).

For reference, XenServer 6.2 shipped with approximately v7 of this
series, and an appropriate kexec-tools and xen-crashdump-analyser.
Since we put the code in, we have not had a single failure-to-kexec in
automated testing (both specific crash tests, and from unexpected host
crashes), whereas we were seeing reliable failures to crash on most of
our test infrastructure.
Verizon is also using an older version back ported to 4.2.1, and we have yet to see a failure in getting into the crash kernel via kexec (it is a very small sample size ~6 Dom0 crashes so far). I have only done 10 crashes so far with v10+ (soon to be v11).
   -Don Slutz
In stark contrast to previous versions of XenServer, we have not had a
single customer reported host crash where the kexec path has failed.
There was one systematic failure where the HPSA driver was unhappy with
the state of the hardware, resulting in no root filesystem to write logs
to, and a repeated panic and Xen deadlock in the queued invalidation


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