Re: [PATCH 3.16 000/132] 3.16.74-rc1 review

[Guenter Roeck]

On Tue, Nov 19, 2019 at 02:58:58PM +0000, Ben Hutchings wrote:
> On Sun, 2019-09-22 at 21:26 +0200, Miguel Ojeda wrote:
> > On Sun, Sep 22, 2019 at 9:04 PM Ben Hutchings <ben@xxxxxxxxxxxxxxx> wrote:
> > > It looks like this is triggered by you switching arm builds from gcc 8
> > > to 9, rather than by any code change.
> > > 
> > > Does it actually make sense to try to support building Linux 3.16 with
> > > gcc 9?  If so, I suppose I'll need to add:
> > > 
> > > commit edc966de8725f9186cc9358214da89d335f0e0bd
> > > Author: Miguel Ojeda <miguel.ojeda.sandonis@xxxxxxxxx>
> > > Date:   Fri Aug 2 12:37:56 2019 +0200
> > > 
> > >     Backport minimal compiler_attributes.h to support GCC 9
> > > 
> > > commit a6e60d84989fa0e91db7f236eda40453b0e44afa
> > > Author: Miguel Ojeda <miguel.ojeda.sandonis@xxxxxxxxx>
> > > Date:   Sat Jan 19 20:59:34 2019 +0100
> > > 
> > >     include/linux/module.h: copy __init/__exit attrs to init/cleanup_module
> > 
> > Yeah, those should fix it.
> 
> A week or two back I tried building 3.16 for x86_64 with gcc 8, which
> produced some warnings but did succeed (and I know Guenter successfully
> build-tests 3.16 with gcc 8 for many architectures).  However, the
> kernel didn't boot on a test system, while the same code built with gcc
> 4.9 (if I remember correctly) did boot.
> 
> While I'm not about to remove support for gcc 8, this makes me think
> that there are some not-so-obvious fixes required to make 3.16 properly
> compatible with recent gcc versions.  So I would rather not continue
> adding superficial support for them, that may lead to people wasting
> time building broken kernels.
> 

I kind of agree. It would make my life easier since I'd be able to drop
older compilers, but on the other side anyone actually using 3.16 kernels
will very likely not update their compilers for the same reason they don't
update the kernel.

Guenter