Re: [PATCH] printf: mark errptr() noinline

[David Laight]

On Wed, 8 Apr 2026 09:24:58 +0200
Petr Mladek <pmladek@xxxxxxxx> wrote:

> On Tue 2026-04-07 16:08:09, David Laight wrote:
> > On Mon, 6 Apr 2026 12:32:32 -0400
> > Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> >   
> > > On Mon, 6 Apr 2026 11:21:39 -0400
> > > Tamir Duberstein <tamird@xxxxxxxxxx> wrote:
> > >   
> > > > Thanks Steve. IMO that is a very big hammer and not warranted in this
> > > > case. There's been talk of encouraging distros to enable CONFIG_KUNIT
> > > > by default [0], which would probably interact poorly with the change
> > > > you propose.
> > > >     
> > > 
> > > Branch profiling is really just a niche that is enabled specifically for
> > > seeing all branches taken in the kernel. It hooks to all "if" statements!
> > > As you can imagine, it causes a rather large overhead in performance.
> > > 
> > > This option is only used by developers doing special analysis of their code
> > > (namely me ;-).  
> > 
> > Is there any way to stop randconfig picking up options like these?
> > It is rather a waste of brain-cycles trying to fix them.
> > If you want the option to test a specific bit of code it is easy to
> > hack/disable any problematic parts.
> > 
> > Even having the KASAN/KMSAN code compiled into allmodconfig is a PITA
> > when you are trying to check that code compiles to something sensible.  
> 
> This does not look like a good idea. KASAN/KMSAN are very useful
> features. People will want to keep them working. Removing them from
> randconfig would just postpone detection of the problem. We would
> need to deal with it sooner or later anyway.

True, but when I build an allmodconfig build to check how the asm looks
I really don't want them.
For the 'bot' builds you also want to know whether they are defined.
Changes to how things are built rather than what is built can throw
up unexpected warnings that are very hard to pin down.

It is bad enough finding things that affect one obscure architecture
with a specific compiler version when the compiler just makes slightly
different decisions, without having unusual compilation/config options
is the mix to muddy the waters further.

	David

> 
> Best Regards,
> Petr