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From: Thomas Monjalon <thomas@monjalon.net>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: dev@dpdk.org, ferruh.yigit@intel.com
Subject: Re: [dpdk-dev] [PATCH] build: check functionality rather than binutils version
Date: Wed, 17 Jun 2020 13:45:57 +0200
Message-ID: <159240636.HSrAOgkoKl@thomas> (raw)
In-Reply-To: <20200617104012.470617-1-bruce.richardson@intel.com>

17/06/2020 12:40, Bruce Richardson:
> Rather than checking the binutils version number, which can lead to
> unnecessary disabling of AVX512 if fixes have been backported to distro
> versions, we can instead check the output of "as" from binutils to see if
> it is correct.
> 
> These checks use the minimal assembly reproduction code posted to the
> public bug tracker for gcc/binutils for those issues [1][2]. If the
> binutils bug is present, the instruction parameters - specifically the
> displacement parameter - will be different in the disassembled output
> compared to the input. Therefore each check involves assembling a single
> instruction and disassembling it again, checking that the two match.

Whaoh, that's a very specific optimization :)
Which distro is affected (backported binutils fix)?

> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90028
> [2] https://sourceware.org/bugzilla/show_bug.cgi?id=23465
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
> --- a/buildtools/meson.build
> +++ b/buildtools/meson.build
> -subdir('pmdinfogen')

Why removing pmdinfogen?

> --- a/meson.build
> +++ b/meson.build
> +# do configuration and get tool paths
> +subdir('buildtools')
>  subdir('config')
>  
>  # build libs and drivers
> -subdir('buildtools')
> +subdir('buildtools/pmdinfogen')

Is it related to binutils check?

[...]
> -	ldver = run_command('ld', '-v').stdout().strip()
> -	if ldver.contains('2.30') and cc.has_argument('-mno-avx512f')
> +	as_ok = run_command(binutils_avx512_check)
> +	if as_ok.returncode() != 0 and cc.has_argument('-mno-avx512f')

"as_ok" is difficult to understand.
I would suggest "binutils_avx512_ok".

> +		message('Binutils error with AVX512 assembly, disabling AVX512 support')

It looks like something which should be part of meson itself.



  reply	other threads:[~2020-06-17 11:46 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-17 10:40 Bruce Richardson
2020-06-17 11:45 ` Thomas Monjalon [this message]
2020-06-17 14:32   ` Bruce Richardson
2020-06-18 11:56 ` [dpdk-dev] [PATCH v2] " Bruce Richardson
2020-06-18 12:05   ` Van Haaren, Harry
2020-07-02 21:28   ` Thomas Monjalon
2020-07-03 10:35     ` Bruce Richardson
2020-07-04 11:48 ` [dpdk-dev] [PATCH v3] " Bruce Richardson
2020-07-05 14:52   ` Thomas Monjalon

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