Re: [Xen-devel] [PATCH v2] xen/arm: allow console=hvc0 to be omitted for guests

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 13/02/2015 15:12, Ard Biesheuvel wrote:
> On 13 February 2015 at 15:03, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> > Hi Ard,
> >
> >
> > On 12/02/2015 19:29, 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@xxxxxxxxxx>
> > > ---
> > >    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 0abeefa7dbf8..927be1d1bad7 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>
> > >
> > > @@ -255,6 +256,9 @@ void __init xen_early_init(void)
> > >                  xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
> > >          else
> > >                  xen_start_info->flags &= ~(SIF_INITDOMAIN|SIF_PRIVILEGED);
> > > +
> > > +       if (!console_set_on_cmdline && !xen_initial_domain())
> > > +               add_preferred_console("hvc", 0, NULL);
> >
> > Unfortunately, this won't work as expected.
> Did you try it?
No just looked at the code.

> > console_set_on_cmdline is set when Linux parses the early params. The
> > parsing is done after setup_arch (the function which call xen_early_init).
> >
> > So we will end up to add the HVC console even if a console has been passed
> > on the command line.
> parse_early_param() is also called by setup_arch(), before xen_early_init()
>
> The call to parse_early_param() in generic code is only there for
> architectures that don't call it in their setup_arch()
Oh, right. Sorry for the noise.

So:

Reviewed-by: Julien Grall <julien.grall@xxxxxxxxxx>

Regards,

--
Julien Grall

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