Re: [Xen-devel] [PATCH v3 4/5] Xen: Select correct dom0 console

[Julien Grall <julien.grall@xxxxxxx>]

Hi Mark,

On 03/01/17 17:29, Mark Rutland wrote:
> On Thu, Dec 15, 2016 at 12:27:17PM +0000, Andre Przywara wrote:
> > From: Ian Campbell <ian.campbell@xxxxxxxxxx>
> >
> > If Xen is enabled, tell Dom0 to use the 'hvc0' console, and fall back to
> > the usual ttyAMA0 otherwise.
> >
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> > Reviewed-by: Julien Grall <julien.grall@xxxxxxx>
> > Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > ---
> >  configure.ac | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/configure.ac b/configure.ac
> > index ea02dca..d23cced 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -105,7 +105,8 @@ AC_ARG_WITH([initrd],
> >  AC_SUBST([FILESYSTEM], [$USE_INITRD])
> >  AM_CONDITIONAL([INITRD], [test "x$USE_INITRD" != "x"])
> >
> > -C_CMDLINE="console=ttyAMA0 earlyprintk=pl011,0x1c090000"
> > +AS_IF([test "x$X_IMAGE" = "x"],[C_CONSOLE="ttyAMA0"],[C_CONSOLE="hvc0"])
> > +C_CMDLINE="console=$C_CONSOLE earlyprintk=pl011,0x1c090000"
> Just to check: what happesns if Dom0 tries to write to 0x1c090000?
Xen is emulating a simple UART (only write is supported) replacing the 
real UART for DOM0. So character will be printed on the console when the 
domain is writing to 0x1c090000.
> Shouldn't we override/delete earlyprintk/earlycon here too?
The ideal would be to use xen console for the earlyprintk/earlycon, but 
it seems that it has not been wired for ARM.
So for now, I would keep the earlyprintk options to help developer 
debugging early crash.
> I've applied this as-is, so if we do need to, I'll need a fixup patch.
Thank you for pushing the series.

Cheers,

--
Julien Grall

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