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

[julien.grall@linaro.org (Julien Grall)]

On 13/02/2015 15:12, Ard Biesheuvel wrote:
> On 13 February 2015 at 15:03, Julien Grall <julien.grall@linaro.org> 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@linaro.org>
>>> ---
>>>    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@linaro.org>

Regards,

-- 
Julien Grall