Re: [PATCH] hw/arm: virt: Add SBSA watchdog

[Jan Kiszka]

On 05.05.22 10:40, Peter Maydell wrote:
> On Sun, 1 May 2022 at 19:07, Jan Kiszka <jan.kiszka@web.de> wrote:
>>
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> The virt machine lacks a watchdog so far while the sbsa-ref has a simple
>> model that is also supported by Linux and even U-Boot. Let's take it to
>> allow, e.g., system integration tests of A/B software update under
>> watchdog monitoring.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> 
> The virt board has a PCI bus, and QEMU has a model of a
> PCI watchdog device -- the i6300esb. Can you use that?

While one could do that, it implies using completely alien Intel x86
host controller bits on this platform. And, thus, would require changes
in firmware (e.g. adding a driver to U-Boot).

> 
> In general I much prefer it if we can support use cases in
> virt via pluggable PCI devices rather than hard-wired MMIO
> devices -- it means that only users who want the functionality
> need to have the exposed attack surface area of the device
> present in their VM.

Valid point - would making this opt-in via a machine feature be sufficient?

Jan

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