Re: [PATCH 3/5] gcov: disable for COMPILE_TEST

From	Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 3/5] gcov: disable for COMPILE_TEST
Date	2016-02-15 15:30 +0100
Message-ID	<r2sk2-2aV-15@gated-at.bofh.it> (permalink)
References	<r1os9-Pl-5@gated-at.bofh.it> <r1os9-Pl-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 12.02.2016 17:06, Arnd Bergmann wrote:
> Enabling gcov is counterproductive to compile testing: it significantly
> increases the kernel image size, compile time, and it produces lots
> of false positive "may be used uninitialized" warnings as the result
> of missed optimizations.
> 
> This is in line with how UBSAN_SANITIZE_ALL and PROFILE_ALL_BRANCHES
> work, both of which have similar problems.
> 
> With an ARM allmodconfig kernel, I see the build time drop from
> 283 minutes CPU time to 225 minutes, and the vmlinux size drops
> from 43MB to 26MB.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Agreed that COMPILE_TEST + GCOV_PROFILE_ALL is a very exotic combination
with little added use.

Acked-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>

> ---
>  kernel/gcov/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
> index c92e44855ddd..1276aabaab55 100644
> --- a/kernel/gcov/Kconfig
> +++ b/kernel/gcov/Kconfig
> @@ -37,6 +37,7 @@ config ARCH_HAS_GCOV_PROFILE_ALL
> 
>  config GCOV_PROFILE_ALL
>  	bool "Profile entire Kernel"
> +	depends on !COMPILE_TEST
>  	depends on GCOV_KERNEL
>  	depends on ARCH_HAS_GCOV_PROFILE_ALL
>  	default n
> 


-- 
Peter Oberparleiter
Linux on z Systems Development - IBM Germany

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 3/5] gcov: disable for COMPILE_TEST Arnd Bergmann <arnd@arndb.de> - 2016-02-12 17:10 +0100
  Re: [PATCH 3/5] gcov: disable for COMPILE_TEST Peter Oberparleiter <oberpar@linux.vnet.ibm.com> - 2016-02-15 15:30 +0100

csiph-web