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From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-trivial@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH 4/4] fix compilation when reconfiguring without dtrace backend
Date: Mon, 09 May 2011 08:53:17 +0200	[thread overview]
Message-ID: <4DC78F5D.7080505@redhat.com> (raw)
In-Reply-To: <BANLkTikq7uuwZOhdFdJD4a1PkHneD6a=Fg@mail.gmail.com>

On 05/08/2011 01:15 PM, Stefan Hajnoczi wrote:
> I think the real problem is that dependencies need to be regenerated
> after ./configure?

There are three ways to do that, the trivial but wrong one, and the 
correct but overzealous one:

- delete .d files.  This forces regeneration of dependencies, but if you 
do not correspondingly delete .o files, you will likely have an 
incomplete build (possibly _nothing_ will be built).

- delete .d and .o files.  This forces regeneration of dependencies and 
recompilation.  True, a lot of distros are using ccache nowadays, but 
still this will cause a complete walk of all directories to pass those 
files to ccache and relink the executables.  It will likely take a 
minute or three.

- detect changes in the configuration and, if those happen, delete .d 
and .o files.  This is the correct one, and for one what the Linux 
kernel makefiles do, but also the biggest effort to implement.

Paolo

  reply	other threads:[~2011-05-09  6:53 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-02  7:54 [Qemu-devel] [PATCH 4/4] fix compilation when reconfiguring without dtrace backend Paolo Bonzini
2011-05-08 11:15 ` [Qemu-devel] [Qemu-trivial] " Stefan Hajnoczi
2011-05-09  6:53   ` Paolo Bonzini [this message]
2011-05-09  8:34     ` Stefan Hajnoczi
2011-05-09  8:42       ` Paolo Bonzini
2011-05-09  9:06         ` Stefan Hajnoczi

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