Re: [PATCH v5] build: update DPDK to use C11 standard

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 10 Aug 2023 18:49:09 +0200
Thomas Monjalon <thomas@monjalon.net> wrote:

> 10/08/2023 18:35, Bruce Richardson:
> > On Thu, Aug 10, 2023 at 07:48:39AM -0700, Stephen Hemminger wrote:  
> > > On Thu, 10 Aug 2023 15:34:43 +0200
> > > Thomas Monjalon <thomas@monjalon.net> wrote:
> > >   
> > > > 03/08/2023 15:36, David Marchand:  
> > > > > On Wed, Aug 2, 2023 at 2:32 PM Bruce Richardson
> > > > > <bruce.richardson@intel.com> wrote:    
> > > > > >
> > > > > > As previously announced, DPDK 23.11 will require a C11 supporting
> > > > > > compiler and will use the C11 standard in all builds.
> > > > > >
> > > > > > Forcing use of the C standard, rather than the standard with
> > > > > > GNU extensions, means that some posix definitions which are not in
> > > > > > the C standard are unavailable by default. We fix this by ensuring
> > > > > > the correct defines or cflags are passed to the components that
> > > > > > need them.
> > > > > >
> > > > > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > > > > Acked-by: Morten Brørup <mb@smartsharesystems.com>
> > > > > > Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>    
> > > > > Tested-by: Ali Alnubani <alialnu@nvidia.com>
> > > > > 
> > > > > The CI results look good.
> > > > > 
> > > > > Applied, thanks!    
> > > > 
> > > > The compiler support is updated, that's fine.
> > > > Should we go further and document some major Linux distributions?
> > > > One concern is to make clear RHEL 7 is not supported anymore.
> > > > Should it be a release note?
> > > >   
> > 
> > Well, DPDK currently is still building fine on Centos 7 for me, so let's
> > hold off on claiming anything until it's definitely broken.
> >   
> > > >   
> > > 
> > > Should be addressed in linux/sys_reqs.rst as well as deprecation notice.
> > > Also, is it possible to add automated check in build for compiler version?  
> > 
> > I'd be a little careful about what we claim, and I think current docs are
> > accurate vs our original plans. What we didn't plan to support was the GCC
> > and Clang compiler versions in RHEL 7, but if one installs an updated GCC,
> > for example, the build should be fine on RHEL 7.
> > 
> > Now, though, we are having to re-evaluate our use of stdatomics, which
> > means we may not actually break RHEL 7 compatibility after all. We'll have
> > to "watch this space" as the saying goes!
> > 
> > Overall, I think the approach of build-time checks is the best, but not
> > for specific versions, but instead for capabilities. If/when we add support
> > for stdatomics to DPDK builds on Linux/BSD, at that point we put in the
> > initial compiler checks a suitable check for them being present and output
> > a suitable error if not found.  
> 
> OK looks good

Note: RHEL 7 official end of maintenance support is not until June 2024.