linux-kernel - Re: [PATCH] gcov: Support for >=gcc-6 missing

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Message-Id: <b660a64f-d8f4-421d-b532-6c53a5c53d84@linux.vnet.ibm.com>
Date:	Thu, 30 Jun 2016 14:13:38 +0200
From:	Peter Oberparleiter <oberpar@...ux.vnet.ibm.com>
To:	Florian Meier <Florian.Meier@...ormatik.uni-erlangen.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gcov: Support for >=gcc-6 missing

On 29.06.2016 16:58, Florian Meier wrote:
> Hello!
> 
> I've noticed problems ("not executed"/ "file empty") with the gcov
> kernel support, when I'm using a gcc version >=6.
> For me, it seems like this is no technical reason, gcc 6 just was
> forgotten in the #ifdefs :).
> 
> The following patch was tested with kernel 4.6.3 and gcc-6.1.1.
> 
> I'm not 100% sure, that CGOV_COUNTERS=10 is correct, but the gcov
> output seemed reasonable.

Looking at the source of GCC 6's gcc/gcov-counter.def I don't see any
new counters added compared to GCC 5.1.0, so GCOV_COUNTERS=10 should
still be correct.

Given that the same situation could again arise with a potential GCC
7.x, adding a "__GNUC__ > 5 ||" to the condition of the existing #if
would be a longer-term solution. Could you re-post the patch with this
change?

> 
> --- a/kernel/gcov/gcc_4_7.c 2016-05-16 00:43:13.000000000 +0200
> +++ b/kernel/gcov/gcc_4_7.c 13:41:41.726666665 +0200
> @@ -18,7 +18,9 @@
>  #include <linux/vmalloc.h>
>  #include "gcov.h"
> 
> -#if __GNUC__ == 5 && __GNUC_MINOR__ >= 1
> +#if __GNUC__ == 6
> +#define GCOV_COUNTERS 10
> +#elif __GNUC__ == 5 && __GNUC_MINOR__ >= 1
>  #define GCOV_COUNTERS 10
>  #elif __GNUC__ == 4 && __GNUC_MINOR__ >= 9
>  #define GCOV_COUNTERS 9
> 
> Regards
> Florian Meier
> 

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