Re: [dpdk-dev] [PATCH v5 2/2] net/hns3: refactor SVE code compile method

[fengchengwen <fengchengwen@huawei.com>]

On 2021/5/19 20:37, David Marchand wrote:
> On Wed, May 19, 2021 at 2:17 PM fengchengwen <fengchengwen@huawei.com> wrote:
>> We also found compile error with gcc8.3 with arm64_kunpeng930_linux_gcc (-march=-march=armv8.2-a+crypto+sve):
>>   In file included from ../dpdk-next-net/lib/eal/common/eal_common_options.c:38:
>>   ../dpdk-next-net/lib/eal/arm/include/rte_vect.h:13:10: fatal error: arm_sve.h: No such file or directory
>>    #include <arm_sve.h>
>>           ^~~~~~~~~~~
>>   compilation terminated.
>>   [126/2250] Compiling C object lib/librte_net.a.p/net_rte_net_crc.c.o
>>
>> the corresponding code:
>>   #ifdef __ARM_FEATURE_SVE
>>   #include <arm_sve.h>
>>   #endif
>>
>> this is because gcc8.3 defined __ARM_FEATURE_SVE but it can't compile ACLE SVE code.
> 
> Afaiu, gcc 8.3 does not define __ARM_FEATURE_SVE:
> 
> $ aarch64-linux-gnu-gcc --version
> aarch64-linux-gnu-gcc (GNU Toolchain for the A-profile Architecture
> 8.3-2019.03 (arm-rel-8.36)) 8.3.0
> Copyright (C) 2018 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> 
> 
> 
> $ aarch64-linux-gnu-gcc - -pipe -E -P -D_FILE_OFFSET_BITS=64 -P -O0
> -march=armv8-a+crc <<EOF
>>         #ifndef __ARM_FEATURE_SVE
>>         # define __ARM_FEATURE_SVE
>>         #endif
>>         "MESON_GET_DEFINE_DELIMITER"
>> __ARM_FEATURE_SVE
>> EOF
>         "MESON_GET_DEFINE_DELIMITER"
> 
> 

You should add sve in '-march' parameter, the same gcc version's output:

 ./aarch64-linux-gnu-gcc --version
aarch64-linux-gnu-gcc (GNU Toolchain for the A-profile Architecture 8.3-2019.03 (arm-rel-8.36)) 8.3.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

./aarch64-linux-gnu-gcc -march=armv8.2-a+sve -dM -E - </dev/null 2>&1 | grep SVE
#define __ARM_FEATURE_SVE 1
#define __ARM_FEATURE_SVE_BITS 0

./aarch64-linux-gnu-gcc -march=armv8-a+sve -dM -E - </dev/null 2>&1 | grep SVE
#define __ARM_FEATURE_SVE 1
#define __ARM_FEATURE_SVE_BITS 0