Re: getting the console output for s390 cdrom-test?

[Peter Maydell]

On Tue, 9 Feb 2021 at 17:24, Cornelia Huck <cohuck@redhat.com> wrote:
>
> On Tue, 9 Feb 2021 17:17:19 +0000
> Peter Maydell <peter.maydell@linaro.org> wrote:
>
> > On Tue, 9 Feb 2021 at 17:10, Cornelia Huck <cohuck@redhat.com> wrote:
> > >
> > > On Tue, 9 Feb 2021 14:58:53 +0000
> > > Peter Maydell <peter.maydell@linaro.org> wrote:
> > > > This change significantly reduces the frequency with which I see
> > > > the hang; but it doesn't get rid of it altogether. Also I couldn't
> > > > really figure out from the virtio spec exactly where barriers
> > > > were required: I think I would need to read the whole thing in
> > > > more detail rather than trying to fish out the information by
> > > > just reading small pieces of it.
> > >
> > > The Linux virtio-ccw code uses 'weak barriers', i.e. the heavy bcr15
> > > should not be needed. We might well miss other (lightweight) barriers
> > > in other parts of the code part, though.
> >
> > Is that the version the Linux kernel has as
> >   /* Fast-BCR without checkpoint synchronization */
> >   #define __ASM_BARRIER "bcr 14,0\n"
> >
> > ?
>
> No, just a simple memory barrier in most places (bcr15 and bcr14 do
> serialization).

OK; if you let me know how that's written for s390 I can give
it a test...

thanks
-- PMM