Re: [dpdk-dev] [PATCH v3] build: use generic march on arm64 when using 'default' machine

[Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>]

On Mon, 2019-01-07 at 14:11 +0000, Luca Boccassi wrote:
> When building for generic distribution we need a stable baseline
> architecture, or depending on the build worker the result will vary.
> 
> Force the default flags if the user explicitly sets machine=default
> at configuration time.
> 
> Fixes: b1d48c41189a ("build: support ARM with meson")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Luca Boccassi <bluca@debian.org>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
> v2: fix typo in commit message, remove variable used only once
> v3: put back temporary variable, as "machine" gets overwritten
>     by the function and loses the original value before we need
>     it.
> 
>  config/arm/meson.build | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build
> index dae55d6b2..614139534 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -6,6 +6,7 @@
>  march_opt = '-march=@0@'.format(machine)
>  
>  arm_force_native_march = false
> +arm_force_default_march = (machine == 'default')
>  
>  machine_args_generic = [
>  	['default', ['-march=armv8-a+crc+crypto']],
> @@ -105,7 +106,11 @@ else
>  	cmd_generic = ['generic', '', '', 'default', '']
>  	cmd_output = cmd_generic # Set generic by default
^
>  	machine_args = [] # Clear previous machine args
> -	if not meson.is_cross_build()
> +	if arm_force_default_march and not meson.is_cross_build()
> +		machine = impl_generic
> +		cmd_output = cmd_generic

Isn't this assignment redundant as it is already done above?

Acked-by: Pavan Nikhilesh <pbhagavatula@marvell.com>

> +		impl_pn = 'default'
> +	elif not meson.is_cross_build()
>  		# The script returns ['Implementer', 'Variant',
> 'Architecture',
>  		# 'Primary Part number', 'Revision']
>  		detect_vendor = find_program(join_paths(