Re: [Qemu-devel] [PULL 0/7] X86 queue, 2015-09-28

[Eduardo Habkost]

On Tue, Sep 29, 2015 at 08:21:49PM +0100, Peter Maydell wrote:
> On 29 September 2015 at 19:22, Eduardo Habkost <address@hidden> wrote:
> > On Tue, Sep 29, 2015 at 12:28:15PM +0100, Peter Maydell wrote:
> >> I get a bunch of new warnings in the course of 'make check' now:
> >>
> >> warning: TCG doesn't support requested feature: CPUID.01H:EDX.de [bit 2]
> >>
> >> /home/petmay01/linaro/qemu-for-merges/target-i386/cpu.c:1494:15:
> >> runtime error: left shift of 1 by 31 places cannot be represented in
> >> type 'int'
> >
> > Which compiler are you using to generate this check?
> 
> That's clang's -fsanitize=undefined (which makes it emit runtime
> warnings about undefined behaviour).

Thanks. I seeing other similar runtime errors in target-i386, I will
take a look at them.

> 
> >
> >>
> >> and also
> >> warning: TCG doesn't support requested feature: CPUID.80000001H:EDX [bit 2]
> >
> > The warnings were expected and will be fixed by the series that
> > implements DE (to be merged soon). But I didn't notice they were so
> > intrusive (and triggered an existing bug at
> > report_unavailable_features()).
> >
> > I will wait until the DE series get included before enabling the
> > warnings in the next pull request. Sorry for the noise.
> 
> Generally we make minor emulation issues report via
> qemu_log(LOG_UNIMP, ...) rather than stderr (and only when
> the guest actually triggers them, ideally). That way you
> only see them if you care.

That warning is for features that were explicitly requested in the
command-line (and in that case, they are not minor issues, because QEMU
is not doing what the user asked for). The bug is that the default CPU
configuration is triggering the warning, but this is going to be fixed
when we add the series implementing Debugging Extensions on TCG.

-- 
Eduardo