Re: [PATCH 12/23] kbuild: avoid re-running compiler and linker probes

[Nicolas Schier]

On Fri, Sep 11, 2026 at 07:24:50PM +0100, Lorenzo Stoakes (ARM) wrote:
> On Fri, Sep 11, 2026 at 08:17:57PM +0200, Nicolas Schier wrote:
> > On Fri, Sep 11, 2026 at 06:33:33PM +0100, David Laight wrote:
> > > On Thu, 10 Sep 2026 17:42:35 +0200
> > > Nicolas Schier <n.schier@xxxxxxxxx> wrote:
> > >
> > > ...
> > > > Yes, skimming through the patch, I thought about that, too.  Moving more
> > > > cc option checks to Kconfig will make building out-of-tree kmods with a
> > > > different compiler more dangerous.  Maybe we will have to make the
> > > > warning in Makefile's prepare (external kmods) target a bit louder.
> > >
> > > One problem is that distributions have a nasty habit of shipping kernels
> > > that are compiled with a different compiler version to they actually
> > > ship as a compiler.
> > > In some cases the versions are clearly the same - but the version
> > > strings differ.
> >
> > yeah, I guess you hit the mark.
> 
> I mean this is a problem that already exists for any flags already specified in
> Kconfig.
> 
> Out-of-tree modules are historically something that we don't go to great lengths
> to support and haven't historically worried about breaking, either.
> 
> I'm sure distros can find ways around this if a problem were to arise. But I
> don't think it's something to worry about all that much.
> 
> I expect a _lot_ of these, in any case, would only require the compilers to be
> within a fair few major versions of one another anyway.

yes, I have similar thoughts about that.  But I think it's good that it 
has been mentioned here in public.

-- 
Nicolas