Re: [dpdk-dev] [PATCH v5 2/2] net/hns3: refactor SVE code compile method

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

<snip>
> 
> Hi, Thomas, Ferruh
> 
> This patch is part of the hns3 SVE compilation solution and can work
> independently. Could you review it ?
I believe this patch is targeted for 20.08 release (as 20.05 is already close to completion), is my understanding correct?
If it is targeted for 20.08, it will give us sometime to do few experiments with the generic approach?

> 
> Best regards
> 
> On 2021/5/14 22:12, Honnappa Nagarahalli wrote:
> > <snip>
> >
> >>
> >> Currently, the SVE code is compiled only when -march supports SVE
> >> (e.g. '- march=armv8.2a+sve'), there maybe some problem[1] with this
> approach.
> >>
> >> The solution:
> >> a. If the minimum instruction set support SVE then compiles it.
> >> b. Else if the compiler support SVE then compiles it.
> >> c. Otherwise don't compile it.
> >>
> >> [1] https://mails.dpdk.org/archives/dev/2021-April/208189.html
> >>
> >> Fixes: 8c25b02b082a ("net/hns3: fix enabling SVE Rx/Tx")
> >> Fixes: 952ebacce4f2 ("net/hns3: support SVE Rx")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> > Looks good to me.
> > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> >
> >> ---
> >>  drivers/net/hns3/hns3_rxtx.c |  2 +-  drivers/net/hns3/meson.build |
> >> 13 +++++++++++++
> >>  2 files changed, 14 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/net/hns3/hns3_rxtx.c
> >> b/drivers/net/hns3/hns3_rxtx.c index 1d7a769..4ef20c6 100644
> >> --- a/drivers/net/hns3/hns3_rxtx.c
> >> +++ b/drivers/net/hns3/hns3_rxtx.c
> >> @@ -2808,7 +2808,7 @@ hns3_get_default_vec_support(void)
> >>  static bool
> >>  hns3_get_sve_support(void)
> >>  {
> >> -#if defined(RTE_ARCH_ARM64) && defined(__ARM_FEATURE_SVE)
> >> +#if defined(CC_SVE_SUPPORT)
> >>  	if (rte_vect_get_max_simd_bitwidth() < RTE_VECT_SIMD_256)
> >>  		return false;
> >>  	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SVE))
> >> diff --git a/drivers/net/hns3/meson.build
> >> b/drivers/net/hns3/meson.build index 53c7df7..8563d70 100644
> >> --- a/drivers/net/hns3/meson.build
> >> +++ b/drivers/net/hns3/meson.build
> >> @@ -35,7 +35,20 @@ deps += ['hash']
> >>
> >>  if arch_subdir == 'arm' and dpdk_conf.get('RTE_ARCH_64')
> >>      sources += files('hns3_rxtx_vec.c')
> >> +
> >> +    # compile SVE when:
> >> +    # a. support SVE in minimum instruction set baseline
> >> +    # b. it's not minimum instruction set, but compiler support
> >>      if cc.get_define('__ARM_FEATURE_SVE', args: machine_args) != ''
> >> +        cflags += ['-DCC_SVE_SUPPORT']
> >>          sources += files('hns3_rxtx_vec_sve.c')
> >> +    elif cc.has_argument('-march=armv8.2-a+sve')
> >> +        cflags += ['-DCC_SVE_SUPPORT']
> >> +        hns3_sve_lib = static_library('hns3_sve_lib',
> >> +                        'hns3_rxtx_vec_sve.c',
> >> +                        dependencies: [static_rte_ethdev],
> >> +                        include_directories: includes,
> >> +                        c_args: [cflags, '-march=armv8.2-a+sve'])
> >> +        objs += hns3_sve_lib.extract_objects('hns3_rxtx_vec_sve.c')
> >>      endif
> >>  endif
> >> --
> >> 2.8.1
> >
> >
> > .
> >