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SubjectRe: [Xen-devel] [PATCH] xen/hvc: If we use xen_raw_printk let it also work on HVM guests.
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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 <520A7145.5010306@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?

Ian.



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