Re: [tip:x86/seves] BUILD SUCCESS WITH WARNING e6eb15c9ba3165698488ae5c34920eea20eaa38e

[Arvind Sankar]

On Tue, Sep 15, 2020 at 02:59:19PM -0700, Nick Desaulniers wrote:
> On Tue, Sep 15, 2020 at 2:50 PM Arvind Sankar <nivedita@xxxxxxxxxxxx> wrote:
> >
> > On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
> > >
> > > (Btw, clang doesn't need to add that "xor %eax,%eax" - panic() should not be
> > >  returning, ever. :-))
> > >
> >
> > I think this is because panic() is varargs, and clang doesn't support
> > gcc's -mskip-rax-setup. The normal ABI requires the caller to set RAX to
> > the number of arguments in vector registers.
> >
> > https://patchwork.ozlabs.org/project/gcc/patch/20141218131150.GA32638@xxxxxxxxx/
> 
> Thanks for the report.  Filed
> https://bugs.llvm.org/show_bug.cgi?id=47538.  Do you have an account
> there Arvind so that I can CC you on them?

Nope, no bugzilla account.

If you're adding flags, another set the kernel uses is the
-falign-{jumps,labels,loops} to turn off alignment of jumps and loops.

> 
> Yikes, it looks like gcc 5.0 supports that.  We'd better get to
> implementing that lest someone try to remove the cc-option on it soon.
> -- 
> Thanks,
> ~Nick Desaulniers