Re: [Ksummit-discuss] [media-submaintainers] [MAINTAINERS SUMMIT] Pull network and Patch Acceptance Consistency

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Mauro,

On Wed, Jun 19, 2019 at 11:39:02AM -0300, Mauro Carvalho Chehab wrote:
> Em Wed, 19 Jun 2019 10:33:23 +0200 Daniel Vetter escreveu:
> > On Wed, Jun 19, 2019 at 9:56 AM Dan Carpenter wrote:
> > > On Mon, Jun 17, 2019 at 10:31:15AM -0300, Mauro Carvalho Chehab wrote:  
> > > > Also, usually, the bots don't build with W=1, as, on most subsystems,
> > > > this cause lots of warnings[1].
> > > >
> > > > [1] On media, we have zero warnings with W=1.
> > >
> > > We could ask the kbuild devs if they would consider making W=1 a per
> > > tree option.  
> > 
> > No need to ask, just add a Kconfig which sets additional cflags for
> > you for your tree and your good. The usual combinatorial testing will
> > discover the new warnings. That's at least what we do for i915.ko
> > (including -Werror). Gets the job done.
> 
> While this works, having a W=1 per tree would, IMHO, work better, as,
> as new warnings get added to W=1, we'll get those for free.
> 
> -
> 
> I don't like the idea of having -Werror being automatically added, as
> this may cause problems when people try to compile with a different
> compiler version - or on some weird architectures.

It's not automatic though, if it depends on a Kconfig option that is
disabled by default. The built bots can enable it, while users would
ignore it. That being said, having it as a per-tree build bot option
should work as well.

> Specially on drivers that build with COMPILE_TEST[1], depending on the 
> architecture they're built, false-positive warnings rise, specially
> on unusual architecture with has different defines for some 
> arch-specific typedefs (signed/unsigned, different integer type,
> usage or not of volatile, a different address space, etc).

All my kernel compilation scripts use -Werror, and that does a great job
at catching problems. It can be a bit annoying at times when someone
introduces a warning, but usually a fix will already be posted when I
notice my build breaks. The more we use -Werror globally, the faster
those new warnings will be caught.

> [1] On media, our goal is that everything should build with
> COMPILE_TEST.

-- 
Regards,

Laurent Pinchart