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Date: Wed, 22 May 2013 14:35:11 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] makefile: detect corrupted elf files
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>, Luiz Capitulino <lcapitulino@redhat.com>, Blue Swirl <blauwirbel@gmail.com>

On Wed, May 22, 2013 at 01:12:15PM +0200, Paolo Bonzini wrote:
> Il 22/05/2013 13:09, Michael S. Tsirkin ha scritto:
> > > Usually I do the same---I just do slightly more thorough testing fo=
r
> > > configure patches.
> >=20
> > I've no idea what happens with ccache on a crash by the way.
> > It's possible that it's careful to do renames in order to not leave
> > corrupted output files behind.
>=20
> It doesn't, it leave 0-sized files.  (Or at least it didn't last time
> power failed during a compilation. :))
>=20
> Paolo

Well looking at the source, there's quite a bit of
handling of renames, so maybe ccache hackers will be
interested in fixing this.

Manpage says:
       It should be noted that ccache is susceptible to general storage
	problems. If a bad object file sneaks into the cache for some reason, it
	will of course stay bad. Some possible reasons for erroneous object
	files are bad hardware (disk drive, disk controller, memory, etc), buggy
	drivers or file systems, a bad CCACHE_PREFIX command or compiler
	wrapper.

	...


       There are no reported issues about ccache producing broken object
       files reproducibly. That doesn=E2=80=99t mean it can=E2=80=99t hap=
pen, so if you find
       a repeatable case, please report it.

power failure is not listed ...

--=20
MST