On 2021/5/14 6:19, Honnappa Nagarahalli wrote:

<snip>

quoted

Currently, the SVE code is compiled only when -march supports SVE (e.g. '-
march=armv8.2a+sve'), there maybe some problem[1] with this approach.

The solution:
a. If the minimum instruction set support SVE then compiles it.
b. Else if the compiler support SVE then compiles it.
c. Otherwise don't compile it.

[1] https://mails.dpdk.org/archives/dev/2021-April/208189.html

Fixes: 8c25b02b082a ("net/hns3: fix enabling SVE Rx/Tx")
Fixes: 952ebacce4f2 ("net/hns3: support SVE Rx")
Cc: stable@dpdk.org

Signed-off-by: Chengwen Feng <redacted>
---
 drivers/net/hns3/hns3_rxtx.c |  2 +-
 drivers/net/hns3/meson.build | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/net/hns3/hns3_rxtx.c b/drivers/net/hns3/hns3_rxtx.c
index 1d7a769..4ef20c6 100644
--- a/drivers/net/hns3/hns3_rxtx.c
+++ b/drivers/net/hns3/hns3_rxtx.c

@@ -2808,7 +2808,7 @@ hns3_get_default_vec_support(void)
 static bool
 hns3_get_sve_support(void)
 {
-#if defined(RTE_ARCH_ARM64) && defined(__ARM_FEATURE_SVE)
+#if defined(CC_SVE_SUPPORT)
 	if (rte_vect_get_max_simd_bitwidth() < RTE_VECT_SIMD_256)
 		return false;
 	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SVE))

diff --git a/drivers/net/hns3/meson.build b/drivers/net/hns3/meson.build
index 53c7df7..8563d70 100644
--- a/drivers/net/hns3/meson.build
+++ b/drivers/net/hns3/meson.build

@@ -35,7 +35,20 @@ deps += ['hash']

 if arch_subdir == 'arm' and dpdk_conf.get('RTE_ARCH_64')
     sources += files('hns3_rxtx_vec.c')
+
+    # compile SVE when:
+    # a. support SVE in minimum instruction set baseline
+    # b. it's not minimum instruction set, but compiler support
     if cc.get_define('__ARM_FEATURE_SVE', args: machine_args) != ''
+        cflags += ['-DCC_SVE_SUPPORT']

Can you please look at commit 21c4f1c7b2f8e637ecff9b9180e21f6b4505715f? This commit removed the CC_SVE_SUPPORT flag due to a compilation error.

The original is cflags = ['-DCC_SVE_SUPPORT'] which will rewrite cflags
And here we use symbol '+=', it only add extra macro which is CC_SVE_SUPPORT
So it's ok.

quoted

         sources += files('hns3_rxtx_vec_sve.c')
+    elif cc.has_argument('-march=armv8.2-a+sve')
+        cflags += ['-DCC_SVE_SUPPORT']
+        hns3_sve_lib = static_library('hns3_sve_lib',
+                        'hns3_rxtx_vec_sve.c',
+                        dependencies: [static_rte_ethdev],
+                        include_directories: includes,
+                        c_args: [cflags, '-march=armv8.2-a+sve'])
+        objs += hns3_sve_lib.extract_objects('hns3_rxtx_vec_sve.c')
     endif
 endif
--
2.8.1

.