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

[Andrew Rybchenko]

@Bruce, see below.

On 7/1/21 3:34 PM, David Marchand wrote:
> On Thu, Jul 1, 2021 at 11:22 AM Andrew Rybchenko
> <andrew.rybchenko at oktetlabs.ru> wrote:
>> The build works fine for me on FC34, but it has
>> libatomic-11.1.1-3.fc34.x86_64 installed.
> 
> I first produced the issue on my "old" FC32.
> Afaics, for FC33 and later, gcc now depends on libatomic and the
> problem won't be noticed.
> FC32 and before are EOL, but I then reproduced the issue on RHEL 8
> (and Intel CI reported it on Centos 8 too).

I see. Thanks for the clarification.

>>
>> 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.
>>
> 
> I tried below diff, and it works for me.
> "works" as in net/sfc gets disabled without libatomic installed:
> 
> diff --git a/drivers/net/sfc/meson.build b/drivers/net/sfc/meson.build
> index 32b58e3d76..8d62aad774 100644
> --- a/drivers/net/sfc/meson.build
> +++ b/drivers/net/sfc/meson.build
> @@ -15,6 +15,7 @@ endif
>  if (arch_subdir != 'x86' or not dpdk_conf.get('RTE_ARCH_64')) and
> (arch_subdir != 'arm' or not
> host_machine.cpu_family().startswith('aarch64'))
>      build = false
>      reason = 'only supported on x86_64 and aarch64'
> +    subdir_done()

@Bruce  Shouldn't we add subdir_done() after all build = false
cases? As I understand it is OK for minimum supported meson
version.

>  endif
> 
>  extra_flags = []
> @@ -46,6 +47,14 @@ endif
> 
>  # for gcc compiles we need -latomic for 128-bit atomic ops
>  if cc.get_id() == 'gcc'
> +    code = '''#include <stdio.h>
> +    void main() { printf("Atomilink me.\n"); }
> +    '''
> +    if not cc.links(code, args: '-latomic', name: 'libatomic link check')
> +        build = false
> +        reason = 'missing dependency, "libatomic"'
> +        subdir_done()
> +    endif
>      ext_deps += cc.find_library('atomic')
>  endif

Many thanks, LGTM. I'll pick it up and add comments why
it is checked this way.