[dpdk-stable] [PATCH 20.11] config/arm: replace native machine args

[Juraj Linkeš]

> -----Original Message-----
> From: luca.boccassi at gmail.com <luca.boccassi at gmail.com>
> Sent: Friday, February 19, 2021 11:58 AM
> To: stable at dpdk.org
> Cc: Juraj Linkeš <juraj.linkes at pantheon.tech>; jerinj at marvell.com;
> ruifeng.wang at arm.com; david.marchand at redhat.com
> Subject: [PATCH 20.11] config/arm: replace native machine args
> 
> From: Juraj Linkeš <juraj.linkes at pantheon.tech>
> 
> [ backported from upstream commit
> 9186e5a07f35ae74a1f7fa2d89671b5f77eae407 ]
> 
> There are compiler issues when building with -mcpu=native with popular
> compilers, such as GCC-8.4:
> In file included from ../lib/librte_eal/arm/include/rte_vect.h:11,
>                  from ../lib/librte_net/net_crc_neon.c:10:
> ../lib/librte_net/net_crc_neon.c: In function ‘crcr32_folding_round’:
> /usr/lib/gcc/aarch64-linux-gnu/8/include/arm_neon.h:26094:1: error:
> inlining failed in call to always_inline ‘vmull_p64’:
> target specific option mismatch
>  vmull_p64 (poly64_t a, poly64_t b)
> ../lib/librte_net/net_crc_neon.c:50:20: note: called from here
>   uint64x2_t tmp1 = vreinterpretq_u64_p128(vmull_p64(
>     vgetq_lane_p64(vreinterpretq_p64_u64(fold), 0),
>     vgetq_lane_p64(vreinterpretq_p64_u64(precomp), 1)));
> 
> and clang:
> gcc -E -dM -mcpu="native" - < /dev/null | grep __ARM_FEATURE_ATOMICS
> clang-9 -E -dM -mcpu="native" - < /dev/null | grep __ARM_FEATURE_ATOMICS
> <no output> # no clang support
> 
> Fix this by always specifying the proper machine args and never using the native
> flags.
> 
> Fixes: 78ac8eac7e8a ("config/arm: use native machine build arguments")
> 
> Signed-off-by: Juraj Linkeš <juraj.linkes at pantheon.tech>
> Signed-off-by: Luca Boccassi <luca.boccassi at microsoft.com>
> ---
> This is a crude backport, but it fixes the build for arm64. It's a release blocker for
> 20.11.1, so I would appreciate a quick review.
> Thanks!

What does this fix? With or without the below change, the native machine args are not used. The patch shoudn't actually change the configuration of the build at all, so I'm a bit confused.

> 
>  config/arm/meson.build | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build index
> 42b4e43c74..8beae4a3f9 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -5,7 +5,6 @@
>  # for checking defines we need to use the correct compiler flags  march_opt = '-
> march=@0@'.format(machine)
> 
> -arm_force_native_march = false
>  arm_force_default_march = (machine == 'default')
> 
>  flags_common_default = [
> @@ -92,7 +91,6 @@ flags_n1generic_extra = [
> 
>  machine_args_generic = [
>  	['default', ['-march=armv8-a+crc', '-moutline-atomics']],
> -	['native', ['-march=native']],
>  	['0xd03', ['-mcpu=cortex-a53']],
>  	['0xd04', ['-mcpu=cortex-a35']],
>  	['0xd07', ['-mcpu=cortex-a57']],
> @@ -104,7 +102,6 @@ machine_args_generic = [
> 
>  machine_args_cavium = [
>  	['default', ['-march=armv8-a+crc+crypto','-mcpu=thunderx']],
> -	['native', ['-march=native']],
>  	['0xa1', ['-mcpu=thunderxt88'], flags_thunderx_extra],
>  	['0xa2', ['-mcpu=thunderxt81'], flags_thunderx_extra],
>  	['0xa3', ['-mcpu=thunderxt83'], flags_thunderx_extra], @@ -112,8
> +109,7 @@ machine_args_cavium = [
>  	['0xb2', ['-march=armv8.2-a+crc+crypto+lse','-mcpu=octeontx2'],
> flags_octeontx2_extra]]
> 
>  machine_args_emag = [
> -	['default', ['-march=armv8-a+crc+crypto', '-mtune=emag']],
> -	['native', ['-march=native']]]
> +	['default', ['-march=armv8-a+crc+crypto', '-mtune=emag']]]
> 
>  ## Arm implementer ID (ARM DDI 0487C.a, Section G7.2.106, Page G7-5321)
> impl_generic = ['Generic armv8', flags_generic, machine_args_generic] @@ -
> 167,9 +163,6 @@ else
>  			cmd_output = cmd_generic
>  		endif
>  		impl_pn = cmd_output[3]
> -		if arm_force_native_march == true
> -			impl_pn = 'native'
> -		endif
>  	else
>  		impl_id = meson.get_cross_property('implementor_id',
> 'generic')
>  		impl_pn = meson.get_cross_property('implementor_pn',
> 'default')
> --
> 2.29.2
>