Re: [dpdk-dev] [PATCH v3] config/arm: split march cfg into arch and features

[Ruifeng Wang <Ruifeng.Wang@arm.com>]

+Pavan 

Hi Chengwen, Pavan,

You had patches to add ability of picking supported march/extension.
Can you help to review this patch and see if the generic infrastructure fulfills your needs?

Regards.
Ruifeng

> -----Original Message-----
> From: Juraj Linkeš <juraj.linkes@pantheon.tech>
> Sent: Monday, July 12, 2021 9:02 PM
> To: thomas@monjalon.net; david.marchand@redhat.com;
> bruce.richardson@intel.com; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang
> <Ruifeng.Wang@arm.com>; fengchengwen@huawei.com;
> ferruh.yigit@intel.com; jerinjacobk@gmail.com; jerinj@marvell.com
> Cc: dev@dpdk.org; Juraj Linkeš <juraj.linkes@pantheon.tech>
> Subject: [PATCH v3] config/arm: split march cfg into arch and features
> 
> Older compilers may not support all arch versions and all features that the
> target SoC supports, in which case it's better to figure out the highest arch
> version and features that the compiler supports. Implement a way to achieve
> this:
> 1. Find the highest arch version that the compiler supports, keeping in mind
> the SoC arch version we're building. For example, if the SoC arch version is
> arm8.2-a, but the compiler only supports arm8.1-a, use arm8.1-a. On the
> other hand, if the compiler supports arm8.3-a (or higher), use armv8.2-a.
> 2. With the architecture version locked, iterate over SoC features and use all
> that are supported.
> 
> In all cases, emit a warning if there's something unsupported by the compiler.
> 
> Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
> ---
> v3: rebase
> ---
>  config/arm/meson.build | 125 ++++++++++++++++++++++++++++++++-----
> ----
>  1 file changed, 100 insertions(+), 25 deletions(-)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build index
> 14987c634a..f5cd30f4f0 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -38,7 +38,9 @@ implementer_generic = {
>      ],
>      'part_number_config': {
>          'generic': {
> -            'machine_args': ['-march=armv8-a+crc', '-moutline-atomics']
> +            'march': 'armv8-a',
> +            'march_features': ['crc'],
> +            'compiler_options': ['-moutline-atomics']
>          },
>          'generic_aarch32': {
>              'machine_args': ['-march=armv8-a', '-mfpu=neon'], @@ -53,15 +55,17
> @@ implementer_generic = {  }
> 
>  part_number_config_arm = {
> -    '0xd03': {'machine_args':  ['-mcpu=cortex-a53']},
> -    '0xd04': {'machine_args':  ['-mcpu=cortex-a35']},
> -    '0xd07': {'machine_args':  ['-mcpu=cortex-a57']},
> -    '0xd08': {'machine_args':  ['-mcpu=cortex-a72']},
> -    '0xd09': {'machine_args':  ['-mcpu=cortex-a73']},
> -    '0xd0a': {'machine_args':  ['-mcpu=cortex-a75']},
> -    '0xd0b': {'machine_args':  ['-mcpu=cortex-a76']},
> +    '0xd03': {'compiler_options':  ['-mcpu=cortex-a53']},
> +    '0xd04': {'compiler_options':  ['-mcpu=cortex-a35']},
> +    '0xd07': {'compiler_options':  ['-mcpu=cortex-a57']},
> +    '0xd08': {'compiler_options':  ['-mcpu=cortex-a72']},
> +    '0xd09': {'compiler_options':  ['-mcpu=cortex-a73']},
> +    '0xd0a': {'compiler_options':  ['-mcpu=cortex-a75']},
> +    '0xd0b': {'compiler_options':  ['-mcpu=cortex-a76']},
>      '0xd0c': {
> -        'machine_args':  ['-march=armv8.2-a+crypto', '-mcpu=neoverse-n1'],
> +        'march': 'armv8.2-a',
> +        'march_features': ['crypto'],
> +        'compiler_options':  ['-mcpu=neoverse-n1'],
>          'flags': [
>              ['RTE_MACHINE', '"neoverse-n1"'],
>              ['RTE_ARM_FEATURE_ATOMICS', true], @@ -71,7 +75,8 @@
> part_number_config_arm = {
>          ]
>      },
>      '0xd49': {
> -        'machine_args':  ['-march=armv8.5-a+crypto+sve2'],
> +        'march': 'armv8.5-a',
> +        'march_features': ['crypto', 'sve2'],
>          'flags': [
>              ['RTE_MACHINE', '"neoverse-n2"'],
>              ['RTE_ARM_FEATURE_ATOMICS', true], @@ -105,19 +110,21 @@
> implementer_cavium = {
>      ],
>      'part_number_config': {
>          '0xa1': {
> -            'machine_args': ['-mcpu=thunderxt88'],
> +            'compiler_options': ['-mcpu=thunderxt88'],
>              'flags': flags_part_number_thunderx
>          },
>          '0xa2': {
> -            'machine_args': ['-mcpu=thunderxt81'],
> +            'compiler_options': ['-mcpu=thunderxt81'],
>              'flags': flags_part_number_thunderx
>          },
>          '0xa3': {
> -            'machine_args': ['-mcpu=thunderxt83'],
> +            'compiler_options': ['-mcpu=thunderxt83'],
>              'flags': flags_part_number_thunderx
>          },
>          '0xaf': {
> -            'machine_args': ['-march=armv8.1-a+crc+crypto', '-
> mcpu=thunderx2t99'],
> +            'march': 'armv8.1-a',
> +            'march_features': ['crc', 'crypto'],
> +            'compiler_options': ['-mcpu=thunderx2t99'],
>              'flags': [
>                  ['RTE_MACHINE', '"thunderx2"'],
>                  ['RTE_ARM_FEATURE_ATOMICS', true], @@ -127,7 +134,9 @@
> implementer_cavium = {
>              ]
>          },
>          '0xb2': {
> -            'machine_args': ['-march=armv8.2-a+crc+crypto+lse', '-
> mcpu=octeontx2'],
> +            'march': 'armv8.2-a',
> +            'march_features': ['crc', 'crypto', 'lse'],
> +            'compiler_options': ['-mcpu=octeontx2'],
>              'flags': [
>                  ['RTE_MACHINE', '"octeontx2"'],
>                  ['RTE_ARM_FEATURE_ATOMICS', true], @@ -148,7 +157,11 @@
> implementer_ampere = {
>          ['RTE_MAX_NUMA_NODES', 1]
>      ],
>      'part_number_config': {
> -        '0x0': {'machine_args':  ['-march=armv8-a+crc+crypto', '-mtune=emag']}
> +        '0x0': {
> +            'march': 'armv8-a',
> +            'march_features': ['crc', 'crypto'],
> +            'compiler_options':  ['-mtune=emag']
> +        }
>      }
>  }
> 
> @@ -160,7 +173,9 @@ implementer_hisilicon = {
>      ],
>      'part_number_config': {
>          '0xd01': {
> -            'machine_args': ['-march=armv8.2-a+crypto', '-mtune=tsv110'],
> +            'march': 'armv8.2-a',
> +            'march_features': ['crypto'],
> +            'compiler_options': ['-mtune=tsv110'],
>              'flags': [
>                  ['RTE_MACHINE', '"Kunpeng 920"'],
>                  ['RTE_ARM_FEATURE_ATOMICS', true], @@ -169,7 +184,8 @@
> implementer_hisilicon = {
>              ]
>          },
>          '0xd02': {
> -            'machine_args': ['-march=armv8.2-a+crypto+sve'],
> +            'march': 'armv8.2-a',
> +            'march_features': ['crypto', 'sve'],
>              'flags': [
>                  ['RTE_MACHINE', '"Kunpeng 930"'],
>                  ['RTE_ARM_FEATURE_ATOMICS', true], @@ -190,8 +206,14 @@
> implementer_qualcomm = {
>          ['RTE_MAX_NUMA_NODES', 1]
>      ],
>      'part_number_config': {
> -        '0x800': {'machine_args':  ['-march=armv8-a+crc']},
> -        '0xc00': {'machine_args':  ['-march=armv8-a+crc']},
> +        '0x800': {
> +            'march': 'armv8-a',
> +            'march_features': ['crc']
> +        },
> +        '0xc00': {
> +            'march': 'armv8-a',
> +            'march_features': ['crc']
> +        }
>      }
>  }
> 
> @@ -500,13 +522,66 @@ if update_flags
>      # add/overwrite flags in the proper order
>      dpdk_flags = flags_common + implementer_config['flags'] +
> part_number_config.get('flags', []) + soc_flags
> 
> -    # apply supported machine args
>      machine_args = [] # Clear previous machine args
> -    foreach flag: part_number_config['machine_args']
> -        if cc.has_argument(flag)
> -            machine_args += flag
> +
> +    # probe supported marchs and their features
> +    candidate_march = ''
> +    if part_number_config.has_key('march')
> +        supported_marchs = ['armv8.6-a', 'armv8.5-a', 'armv8.4-a', 'armv8.3-a',
> +                            'armv8.2-a', 'armv8.1-a', 'armv8-a']
> +        check_compiler_support = false
> +        foreach supported_march: supported_marchs
> +            if supported_march == part_number_config['march']
> +                # start checking from this version downwards
> +                check_compiler_support = true
> +            endif
> +            if (check_compiler_support and
> +                cc.has_argument('-march=' + supported_march))
> +                candidate_march = supported_march
> +                # highest supported march version found
> +                break
> +            endif
> +        endforeach
> +        if candidate_march == ''
> +            error('No suitable armv8 march version found.')
> +        else
> +            if candidate_march != part_number_config['march']
> +                warning('Configuration march version is ' +
> +                        '@0@, but the compiler supports only @1@.'
> +                        .format(part_number_config['march'], candidate_march))
> +            endif
> +            candidate_march = '-march=' + candidate_march
>          endif
> -    endforeach
> +        if part_number_config.has_key('march_features')
> +            feature_unsupported = false
> +            foreach feature: part_number_config['march_features']
> +                if cc.has_argument('+'.join([candidate_march, feature]))
> +                    candidate_march = '+'.join([candidate_march, feature])
> +                else
> +                    feature_unsupported = true
> +                endif
> +            endforeach
> +            if feature_unsupported
> +                warning('Configuration march features are ' +
> +                        '@0@, but the compiler supports only @1@.'
> +                        .format(part_number_config['march_features'],
> +                                candidate_march))
> +            endif
> +        endif
> +        machine_args += candidate_march
> +    endif
> +
> +    # apply supported compiler options
> +    if part_number_config.has_key('compiler_options')
> +        foreach flag: part_number_config['compiler_options']
> +            if cc.has_argument(flag)
> +                machine_args += flag
> +            else
> +                warning('Configuration compiler option ' +
> +                        '@0@ isn\'t supported.'.format(flag))
> +            endif
> +        endforeach
> +    endif
> 
>      # apply flags
>      foreach flag: dpdk_flags
> --
> 2.20.1