Re: [dpdk-dev] [PATCH v3] mk: fix scope of disabling AVX512F support

[Yongseok Koh]

> On Jan 3, 2019, at 8:23 AM, Ferruh Yigit <ferruh.yi...@intel.com> wrote:
> 
> AVX512 was disabled for GCC because of Bugzilla issue 97 [1],
> the GCC defect submitted for the issue [2] highlighted that this is
> a known binutils version 2.30 issue.
> 
> Narrowed the scope of no-avx512 to the this specific binutils version.
> 
> [1]
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.dpdk.org%2Fshow_bug.cgi%3Fid%3D97&amp;data=02%7C01%7Cyskoh%40mellanox.com%7C9e8d0eb500ca4cb74c1508d67197c6b0%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636821294022213177&amp;sdata=Rxj7HxBWfp4hMzfRkiGtnSYt8N0TG9xnAL0ZYBpYYa0%3D&amp;reserved=0
> 
> [2]
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fbugzilla%2Fshow_bug.cgi%3Fid%3D88096&amp;data=02%7C01%7Cyskoh%40mellanox.com%7C9e8d0eb500ca4cb74c1508d67197c6b0%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636821294022213177&amp;sdata=EqzsamoYfFve5JAsgyWw51JOBhhiKTOCrnfZoYTGN28%3D&amp;reserved=0
> 
> Fixes: 8d07c82b239f ("mk: disable gcc AVX512F support")
> Cc: sta...@dpdk.org
> 
> Signed-off-by: Ferruh Yigit <ferruh.yi...@intel.com>
> ---
Acked-by: Yongseok Koh <ys...@mellanox.com>
 
Thanks

> Cc: Tom Barbette <barbe...@kth.se>
> Cc: Thomas Monjalon <tho...@monjalon.net>
> Cc: Yongseok Koh <ys...@mellanox.com>
> Cc: Konstantin Ananyev <konstantin.anan...@intel.com>
> Cc: Bruce Richardson <bruce.richard...@intel.com>
> 
> v2:
> * Added warning message (print only once for eal)
> * Moved decision details to compat file, kept execution in cpuflags
> 
> v3:
> * replace 'ld' with '$(LD)' for cross build
> * added meson support
> ---
> config/meson.build                       |  8 ++++++++
> mk/rte.cpuflags.mk                       |  4 ++--
> mk/toolchain/gcc/rte.toolchain-compat.mk | 10 ++++++++++
> 3 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/config/meson.build b/config/meson.build
> index db32499b3..40802fc88 100644
> --- a/config/meson.build
> +++ b/config/meson.build
> @@ -43,6 +43,14 @@ toolchain = cc.get_id()
> dpdk_conf.set_quoted('RTE_TOOLCHAIN', toolchain)
> dpdk_conf.set('RTE_TOOLCHAIN_' + toolchain.to_upper(), 1)
> 
> +# get binutils version for the workaround of Bug 97
> +ldver = run_command('ld', '-v').stdout().strip()
> +if ldver.contains('2.30')
> +     if cc.has_argument('-mno-avx512f')
> +             machine_args += '-mno-avx512f'
> +     endif
> +endif
> +
> add_project_link_arguments('-Wl,--no-as-needed', language: 'c')
> dpdk_extra_ldflags += '-Wl,--no-as-needed'
> 
> diff --git a/mk/rte.cpuflags.mk b/mk/rte.cpuflags.mk
> index c3291b17a..541211c61 100644
> --- a/mk/rte.cpuflags.mk
> +++ b/mk/rte.cpuflags.mk
> @@ -69,8 +69,8 @@ ifneq ($(filter $(AUTO_CPUFLAGS),__AVX512F__),)
> ifeq ($(CONFIG_RTE_ENABLE_AVX512),y)
> CPUFLAGS += AVX512F
> else
> -# disable AVX512F support of gcc as a workaround for Bug 97
> -ifeq ($(CONFIG_RTE_TOOLCHAIN_GCC),y)
> +# disable AVX512F support for GCC & binutils 2.30 as a workaround for Bug 97
> +ifeq ($(FORCE_DISABLE_AVX512),y)
> MACHINE_CFLAGS += -mno-avx512f
> endif
> endif
> diff --git a/mk/toolchain/gcc/rte.toolchain-compat.mk 
> b/mk/toolchain/gcc/rte.toolchain-compat.mk
> index 44904295c..33ea3f03a 100644
> --- a/mk/toolchain/gcc/rte.toolchain-compat.mk
> +++ b/mk/toolchain/gcc/rte.toolchain-compat.mk
> @@ -20,6 +20,16 @@ HOST_GCC_MINOR = $(shell echo __GNUC_MINOR__ | $(HOSTCC) 
> -E -x c - | tail -n 1)
> HOST_GCC_PATCHLEVEL = $(shell echo __GNUC_PATCHLEVEL__ | $(HOSTCC) -E -x c - 
> | tail -n 1)
> HOST_GCC_VERSION = $(HOST_GCC_MAJOR)$(HOST_GCC_MINOR)
> 
> +LD_VERSION = $(shell $(LD) -v)
> +# disable AVX512F support for GCC & binutils 2.30 as a workaround for Bug 97
> +ifneq ($(filter 2.30%,$(LD_VERSION)),)
> +FORCE_DISABLE_AVX512 := y
> +# print warning only once for librte_eal
> +ifneq ($(filter %librte_eal,$(lastword $(CURDIR))),)
> +$(warning AVX512 support disabled because of ld 2.30. See Bug 97)
> +endif
> +endif
> +
> # if GCC is older than 4.x
> ifeq ($(shell test $(GCC_VERSION) -lt 40 && echo 1), 1)
>       MACHINE_CFLAGS =
> -- 
> 2.17.2
>