On Thu, Feb 22, 2024 at 1:45 PM <pbhagavat...@marvell.com> wrote:
>
> From: Pavan Nikhilesh <pbhagavat...@marvell.com>
>
> Some ARM CPUs have specific march requirements and
> are not compatible with the supported march list.
> Add fallback march in case the mcpu and the march
> advertised in the part_number_config are not supported
> by the compiler.
>
> Example
> mcpu = neoverse-n2
> march = armv9-a
> fallback_march = armv8.5-a
>
> mcpu, march not supported
> machine_args = ['-march=armv8.5-a']
>
> mcpu, march, fallback_march not supported
> least march supported = armv8-a
>
> machine_args = ['-march=armv8-a']
>
> Signed-off-by: Pavan Nikhilesh <pbhagavat...@marvell.com>
> ---
> config/arm/meson.build | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/config/arm/meson.build b/config/arm/meson.build
> index d05d54b564..87ff5039f6 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -94,6 +94,7 @@ part_number_config_arm = {
> '0xd49': {
> 'march': 'armv9-a',
> 'march_features': ['sve2'],
> + 'fallback_march': 'armv8.5-a',
> 'mcpu': 'neoverse-n2',
> 'flags': [
> ['RTE_MACHINE', '"neoverse-n2"'],
> @@ -708,6 +709,7 @@ if update_flags
>
> candidate_mcpu = ''
> candidate_march = ''
> + fallback_march = ''
>
> if part_number_config.has_key('mcpu') and
> cc.has_argument('-mcpu=' + part_number_config['mcpu'])
> @@ -736,16 +738,22 @@ if update_flags
> # start checking from this version downwards
> check_compiler_support = true
> endif
> - if (check_compiler_support and
> + if (check_compiler_support and candidate_march == '' and
> cc.has_argument('-march=' + supported_march))
> candidate_march = supported_march
> - # highest supported march version found
> - break
> + endif
> + if (part_number_config.has_key('fallback_march') and
> + supported_march == part_number_config['fallback_march']
> and
> + cc.has_argument('-march=' + supported_march))
> + fallback_march = supported_march
If both fallback_march and march are supported, fallback_march is
going to be chosen over march. I think this is what we want instead:
Use march if supported,
then use fallback_march if supported,
then use the other fallback marchs.
If the above is indeed what we want, we could just put this after
endforeach (in the original version):
# at this point, candidate march is either
part_number_config['fallback_march'] or some other lower version
if (part_number_config.has_key('fallback_march') and
candidate_march != part_number_config['march'] and
cc.has_argument('-march=' + part_number_config['fallback_march']))
# this overwrites only the lower version with preferred
fallback_march, if supported
candidate_march = part_number_config['fallback_march']
endif
This way we won't even need the fallback_march variable.
> endif
> endforeach
> endif
>
> if candidate_march != part_number_config['march']
> + if fallback_march != ''
> + candidate_march = fallback_march
> + endif
> warning('Configuration march version is @0@, not supported.'
> .format(part_number_config['march']))
> if candidate_march != ''
> --
> 2.25.1
>
