Re: [dpdk-dev] [PATCH v3 19/20] net/sfc: support flow action COUNT in transfer rules

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 6/21/21 12:30 PM, Thomas Monjalon wrote:
> 21/06/2021 10:28, David Marchand:
>> On Fri, Jun 18, 2021 at 3:41 PM Andrew Rybchenko
>>> +# for gcc compiles we need -latomic for 128-bit atomic ops
>>> +if cc.get_id() == 'gcc'
>>> +    ext_deps += cc.find_library('atomic')
>>> +endif
>>
>> This patch breaks compilation on rhel/fedora (most failures in UNH for
>> this series are linked to this issue) when the libatomic rpm is not
>> installed.
> [...]
>> """
>> Running compile:
>> Working directory:
>> /home/dmarchan/builds/build-gcc-static/meson-private/tmpdu27j15z
>> Command line:  gcc -L/home/dmarchan/intel-ipsec-mb/install/lib
>> -I/home/dmarchan/intel-ipsec-mb/install/include
>> /home/dmarchan/builds/build-gcc-static/meson-private/tmpdu27j15z/testfile.c
>> -o /home/dmarchan/builds/build-gcc-static/meson-private/tmpdu27j15z/output.exe
>> -pipe -D_FILE_OFFSET_BITS=64 -O0 -Wl,--start-group -latomic
>> -Wl,--end-group -Wl,--allow-shlib-undefined
>>
>> Code:
>>  int main(void) { return 0; }
>>
>> Compiler stdout:
>>
>> Compiler stderr:
>>  /usr/bin/ld: cannot find /usr/lib64/libatomic.so.1.2.0
>> collect2: error: ld returned 1 exit status
>>
>> Library atomic found: YES
>> """
> 
> Indeed it looks like a bug in meson.
> 
> How does it behave with clang 32-bit?
> 
> For reference, in config/meson.build:
> """
> # for clang 32-bit compiles we need libatomic for 64-bit atomic ops
> if cc.get_id() == 'clang' and dpdk_conf.get('RTE_ARCH_64') == false
>     atomic_dep = cc.find_library('atomic', required: true)
>     add_project_link_arguments('-latomic', language: 'c')
>     dpdk_extra_ldflags += '-latomic'
> endif
> """
> 
>> [dmarchan@wsfd-netdev66 dpdk]$ cat
>> /usr/lib/gcc/x86_64-redhat-linux/10/libatomic.so
>> INPUT ( /usr/lib64/libatomic.so.1.2.0 )
>> [dmarchan@wsfd-netdev66 dpdk]$ file /usr/lib64/libatomic.so.1.2.0
>> /usr/lib64/libatomic.so.1.2.0: cannot open
>> `/usr/lib64/libatomic.so.1.2.0' (No such file or directory)
> 
> We must handle this case where libatomic is not completely installed.
> 
> Hope there is a good fix possible.
> 

The build works fine for me on FC34, but it has
libatomic-11.1.1-3.fc34.x86_64 installed.

I'd like to understand what we're trying to solve here.
Are we trying to make meson to report the missing library
correctly?

If so, I think I can do simple check using cc.links()
which will fail if the library is not found. I'll
test that it works as expected if the library is not
completely installed.