Re: [PATCH] xen/rpi4: implement watchdog-based reset

[Julien Grall <julien@xxxxxxx>]

Hi,

On 04/06/2020 17:24, Stefano Stabellini wrote:
> On Thu, 4 Jun 2020, André Przywara wrote:
> > On 04/06/2020 09:48, Julien Grall wrote:
> >
> > Hi,
> >
> > > On 03/06/2020 23:31, Stefano Stabellini wrote:
> > > > Touching the watchdog is required to be able to reboot the board.
> > > In general the preferred method is PSCI. Does it mean RPI 4 doesn't
> > > support PSCI at all?
> > There is mainline Trusted Firmware (TF-A) support for the RPi4 for a few
> > months now, which includes proper PSCI support (both for SMP bringup and
> > system reset/shutdown). At least that should work, if not, it's a bug.
> > An EDK-2 build for RPi4 bundles TF-A automatically, but you can use TF-A
> > without it, with or without U-Boot: It works as a drop-in replacement
> > for armstub.bin. Instruction for building it (one line!) are here:
> > https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/docs/plat/rpi4.rst
> >
> > > > The implementation is based on
> > > > drivers/watchdog/bcm2835_wdt.c:__bcm2835_restart in Linux.
> > > Can you give the baseline? This would allow us to track an issue and
> > > port them.
> > Given the above I don't think it's a good idea to add extra platform
> > specific code to Xen.
> The RPi4, at least the one I have, doesn't come with any TF, and it
> doesn't come with PSCI in device tree. As a user, I would rather have
> this patch (even downstream) than having to introduce TF in my build and
> deployment just to be able to reboot.
So what are you using for the firmware? Do you boot Xen directly?

Cheers,

--
Julien Grall