On Tue, Aug 13, 2013 at 11:20:05PM +0100, Ian Campbell wrote:
> On Tue, 2013-08-13 at 21:59 +0100, Ian Campbell wrote:
>
> > > What it should be is:
> > > > >
> > > > > void xen_raw_console_write(const char *str)
> > > > > {
> > > > > - dom0_write_console(0, str, strlen(str));
> > > > > + if (!xen_domain())
> > > > > + return;
> > > > > +
> > > > > + if (xen_pv_domain())
> > > xen_domain()
> > >
> > > > > + dom0_write_console(0, str, strlen(str));
> > > > > + else if (xen_hvm_domain() || xen_cpuid_base()) {
> > >
> > > else if (xen_cpuid_base()) {
> > >
> > > > > + /* The hyperpage has not been setup yet. */
> > > > > + int i, len = strlen(str);
> > > > > + for (i = 0; i < len; i++)
> > > > > + outb(str[i], 0xe9);
> > > > > + }
> > > > > }
> > >
> > > And then that should adhere to what I wrote up.
> >
> > I think it does too.
>
> Except as Daniel notes in <520a7145.5010...@tycho.nsa.gov> for unrelated
> reasons:
>
> > HVM guests can still use the PV output - they just need to use the
> > console
> > write hypercall instead of the HVM I/O port. I would think that PVH
> > guests
> > would default to using the hypercall as it is more efficient (it
> > takes a
> > string rather than one character per write).
> >
> > Actually, checking... the console_io hypercall would need to be
> > added to
> > the hvm_hypercall{32,64}_table for an HVM guest to be able to use
> > it; they
> > currently must use the I/O port. I didn't check the PVH patches.
>
> Or did you actually try this code and it worked?
The one I typed up above - no. The one I had sent - yes.
But with that above mentioned comment from Daniel I think it is still
worth trying to do dom0_write_console and if the hypercall returns -ENOSYS
then fall back on 0xe9.
And lastly send an patch to make hypercall_io work under HVM.
>
> Ian.
>
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