[PATCH] xen/arm: allow console=hvc0 to be omitted for guests

[ian.campbell@citrix.com (Ian Campbell)]

On Tue, 2015-02-10 at 07:00 +0000, Stefano Stabellini wrote:
> On Fri, 30 Jan 2015, Ard Biesheuvel wrote:
> > This patch registers hvc0 as the preferred console if no console
> > has been specified explicitly on the kernel command line.
> > 
> > The purpose is to allow platform agnostic kernels and boot images
> > (such as distro installers) to boot in a Xen/ARM domU without the
> > need to modify the command line by hand.
> > 
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
> > 
> > This applies on top of the patch Julien is cooking up to move the
> > call to xen_guest_init() to an earlier boot stage. This needs to
> > be at least before the call to console_init() in start_kernel()
> > for this patch to do anything meaningful.
> 
> This patch looks good but there isn't much point in queuing this up
> without the prerequisite.
> 
> Julien, what patch exactly is that? What is the status of it?
> 
> 
> >  arch/arm/xen/enlighten.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> > index c7ca936ebd99..61382cafa877 100644
> > --- a/arch/arm/xen/enlighten.c
> > +++ b/arch/arm/xen/enlighten.c
> > @@ -24,6 +24,7 @@
> >  #include <linux/cpuidle.h>
> >  #include <linux/cpufreq.h>
> >  #include <linux/cpu.h>
> > +#include <linux/console.h>
> >  
> >  #include <linux/mm.h>
> >  
> > @@ -322,6 +323,9 @@ static int __init xen_guest_init(void)
> >  
> >  	register_cpu_notifier(&xen_cpu_notifier);
> >  
> > +	if (!console_set_on_cmdline)
> > +		add_preferred_console("hvc", 0, NULL);

FWIW on x86 this doesn't depend on console_set_on_cmdline, does it need
to here?

On x86 it does depend on !xen_initial_domain. I suppose on the principal
that a VT is normally available there. I suppose that doesn't apply to
ARM so much, although it could.

> > +
> >  	return 0;
> >  }
> >  early_initcall(xen_guest_init);
> > -- 
> > 1.8.3.2
> >