linux-kernel - Re: [PATCH] kbuild: work around distcc/icecc madness

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Message-ID: <20090320092234.GA3792@elte.hu>
Date:	Fri, 20 Mar 2009 10:22:34 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Sam Ravnborg <sam@...nborg.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] kbuild: work around distcc/icecc madness


* Thomas Gleixner <tglx@...utronix.de> wrote:

> Impact: workaround for distcc/icecc
> 
> Peter and I noticed that distcc and icecc based kernel compiles
> started to show random full kernel rebuilds even when nothing or just
> a .c file changed. The reason is "change of the command line" which
> caused scripts/mod/empty.o to rebuild and due to the dependencies the
> complete kernel tree. I never change the command line simply because I
> use a script for my builds.
> 
> The root cause for this problem is the check for the CFI support in
> x86 binutils. The call is generated via:
> 
>     echo -e "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -xassembler -o "$$TMP" -
> 
> This works fine as long as a local gcc is used or distcc/icecc use the
> local machine. When distcc/icecc offload the compile to a remote
> machine the compile fails with the following error message:
>    gcc: : No such file or directory
> 
> Now we get command lines with -DCONFIG_CFI* and without every other
> compile which causes the full rebuilds.
> 
> Digging trough the distcc/icecc code it seems that the stdin input for
> remote compiles is not handled correctly. Indeed there is some strange
> comment about this, but unfortunately no decision to compile it
> local. :(
> 
> distcc and icecc are used by many developers and we can not fix the
> versions which are out there in the wild, but we can avoid the stdin
> based call easily: echo the asm code into the temp file which is used
> for the output and use it as input file for the compiler.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> 
> ---
>  scripts/Kbuild.include |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Doesnt fully work:

arch/x86/kernel/entry_32.S:346: Error: unknown pseudo-op: `.cfi_signal_frame'
arch/x86/kernel/entry_32.S:394: Error: unknown pseudo-op: `.cfi_signal_frame'
arch/x86/kernel/entry_32.S:519: Error: unknown pseudo-op: `.cfi_signal_frame'
arch/x86/kernel/entry_32.S:614: Error: unknown pseudo-op: `.cfi_signal_frame'
arch/x86/kernel/entry_32.S:685: Error: unknown pseudo-op: `.cfi_signal_frame'
arch/x86/kernel/entry_32.S:754: Error: unknown pseudo-op: `.cfi_signal_frame'

config attached. Distcc driven build.

	Ingo

View attachment "config" of type "text/plain" (64388 bytes)