linux-kernel - [PATCH] x86: Disable CONFIG_X86_DECODER

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Date:	Wed, 5 Feb 2014 06:51:37 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
	Richard Weinberger <richard@....at>,
	Borislav Petkov <bp@...e.de>
Subject: [PATCH] x86: Disable CONFIG_X86_DECODER_SELFTEST in
 allmod/allyesconfigs


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> > BTW you probably also want to do the same for the x86 instruction 
> > decoder test. It seems to be the biggest compile time waster in 
> > allyesconfig and I usually disable it too.
> 
> Agreed, that should be disabled too by default. Although in that 
> case I think the COMPILE_TEST combination makes more sense, since 
> it's a coverage issue.

I'd say randconfig will cover it often enough, and the failure is also 
borderline build coverage related: you cannot really make the decoder 
test fail via source level changes, only with changes in the build 
environment, so I agree with Andi that we can disable this one too - 
via the patch below.

Thanks,

	Ingo

Signed-off-by: Ingo Molnar <mingo@...nel.org>

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 0f3621e..f0fca39 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -184,6 +184,11 @@ config HAVE_MMIOTRACE_SUPPORT
 config X86_DECODER_SELFTEST
 	bool "x86 instruction decoder selftest"
 	depends on DEBUG_KERNEL && KPROBES
+	#
+	# It can take some time to validate the image,
+	# make sure {allyes|allmod}config doesn't enable it:
+	#
+	depends on !COMPILE_TEST
 	---help---
 	 Perform x86 instruction decoder selftests at build time.
 	 This option is useful for checking the sanity of x86 instruction
--
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