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Date: Wed, 22 May 2013 13:50:34 +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 12:40:23PM +0200, Paolo Bonzini wrote:
> Il 22/05/2013 11:42, Michael S. Tsirkin ha scritto:
> > On Wed, May 22, 2013 at 11:22:52AM +0200, Paolo Bonzini wrote:
> >> Il 22/05/2013 10:52, Michael S. Tsirkin ha scritto:
> >>> The fix is simple here: don't use ccache.  I don't.
> >>>
> >>> In fact, from what I saw people use ccache to work around makefile bugs,
> >>> so they can do make clean; make and have it finish quickly.
> >>>
> >>> Any other examples?
> >>
> >> Testing configure patches should be done (also) from a clean build
> >> directory, for example.
> >>
> >> Paolo
> > 
> > In fact, relying on make clean for testing the build
> > system is a mistake.  It's easy for it to forget to
> > remove some temporary file. You really should do
> > a clean clone.
> 
> Yes, I use a clean clone (and a clean build directory for each patch),
> _hence_ ccache helps reducing test times.
> 
> Paolo

I see, this workflow is the exact reverse of mine:

I do as much as possible in a single tree so I
rely on the makefile dependencies to be correct
to rebuild the right things.

You don't need so many dependencies: just enough
to pull the right bits from the cache.

I can see how any patches correcting in-place rebuilds
won't scratch any of your itches.

-- 
MST