Re: [dpdk-dev] [PATCH] config/arm: add ability to express arch extensions

[Thomas Monjalon <thomas@monjalon.net>]

05/05/2021 14:14, pbhagavatula@marvell.com:
> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
> 
> The ARM architecture allows SoCs to have extensions in addition
> to base profiles such as Large System Extension (LSE), CRC etc.
> 
> Add ability to declare SoC specific extensions.
> 
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>

I don't know what it is fixing. It is an optimization?
Is it candidate for next release?

> ---
> 
>  More details about ARM extensions
>  https://developer.arm.com/documentation/102378/0200
> 
>  config/arm/meson.build | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build
> index 22cd81319..8aa961e5b 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -230,6 +230,7 @@ soc_cn10k = {
>          ['RTE_MAX_LCORE', 24],
>          ['RTE_MAX_NUMA_NODES', 1]
>      ],
> +    'extensions' : ['lse', 'crc'],
>      'part_number': '0xd49',
>      'numa': false
>  }
> @@ -387,6 +388,7 @@ else
>      endif
> 
>      soc_flags = []
> +    soc_extensions = []
>      if soc_config.has_key('not_supported')
>          error('SoC @0@ not supported.'.format(soc))
>      elif soc_config != {}
> @@ -394,6 +396,7 @@ else
>          implementer_config = implementers[implementer_id]
>          part_number = soc_config['part_number']
>          soc_flags = soc_config.get('flags', [])
> +        soc_extensions = soc_config.get('extensions', [])
>          if not soc_config.get('numa', true)
>              has_libnuma = 0
>          endif
> @@ -431,6 +434,11 @@ else
>      # apply supported machine args
>      machine_args = [] # Clear previous machine args
>      foreach flag: part_number_config['machine_args']
> +        if flag.startswith('-march') and soc_extensions.length() != 0

Why condition on start with -march?

> +            foreach ex: soc_extensions
> +                flag += '+' + ex
> +            endforeach
> +        endif