<snip>

On Wed, May 12, 2021 at 2:01 PM Chengwen Feng
[off-list ref] wrote:

quoted

Currently, the soc_kunpeng930 declares '-march=armv8.2-a+crypto+sve',
but some compiler doesn't recognize the march because it doesn't
support sve.

Agree with the problem statement.

+ @Juraj Linkeš

quoted

This patch adds '-march=armv8.2-a+crypto' before
'-march=armv8.2-a+crypto+sve' so that:
1. If compiler doesn't support '-march=armv8.2-a+crypto+sve', then it
will fallback supports 'armv8.2-a+crypto'.
2. If compiler supports '-march=armv8.2-a+crypto+sve', then it will
compile SVE-related code.

Fixes: 7cf32a22b240 ("config/arm: add Hisilicon kunpeng")

Signed-off-by: Chengwen Feng <redacted>
---
 config/arm/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config/arm/meson.build b/config/arm/meson.build index

3f34ec9..fe6c29b 100644

--- a/config/arm/meson.build
+++ b/config/arm/meson.build

@@ -158,7 +158,7 @@ implementer_hisilicon = {
             ]
         },
         '0xd02': {
-            'machine_args': ['-march=armv8.2-a+crypto+sve'],
+            'machine_args': ['-march=armv8.2-a+crypto',
+ '-march=armv8.2-a+crypto+sve'],

I think, this problem not specific to Kunpeng. I think, in order to have a generic
solution, I think, we need to express something like [[armv8.2-a], [crypto],
[sve]] or so in the code and any infra code can generate a working
combination to avoid duplicating the combination manually in code and have
some generic solution for all the platforms.

I think this approach will be too generic. We have to start with v8.0 (as the compiler might not support v8.2-a) and list every feature and check if all those features are supported in the compiler. It might be required that some features might not perform well in certain applications which requires for disabling the features.

I think tweaks like this should be left to the end user.

i.e
patch 1: Enable the infrastructure for auto probe based on compiler support.
patch 2: Fix existing machines including the Kunpeng.

quoted

             'flags': [
                 ['RTE_MACHINE', '"Kunpeng 930"'],
                 ['RTE_ARM_FEATURE_ATOMICS', true],
--
2.8.1