On Thu, Jul 17 2025, Daniel P. Berrangé <berra...@redhat.com> wrote:
> On Thu, Jul 17, 2025 at 05:17:42PM +0200, Cornelia Huck wrote:
>> On Tue, Jul 15 2025, Daniel P. Berrangé <berra...@redhat.com> wrote:
>>
>> > On Tue, Jul 15, 2025 at 09:16:24AM -0700, Andrea Bolognani wrote:
>> >> You can point them to documentation over and over again, or you can
>> >> work to prevent the confusion/annoyance from showing up in the first
>> >> place. Which of the two approaches is a better use of anyone's time
>> >> is up for debate.
>> >>
>> >> I for one am grateful that someone put the time in all those years
>> >> ago and, as a result, PCI and USB controllers don't suffer from the
>> >> problem today. Ultimately it's up to Connie though.
>> >
>> > The PCI/USB controller situation is not the same tradeoff though.
>> > Those guest kernel drivers will identify and attach to these two
>> > controllers regardless of their PCI vendor/product, via the PCI
>> > class property. In that case changing the PCI ID and other device
>> > metadata in QEMU is cheap as it has no negative impact on guest OS
>> > driver compibility.
>> >
>> > In the case of 6300ESB though the guest driver is tied directly to
>> > the currently used PCI device product/vendor ID.
>> >
>> > If we change this then we have actually created new functional
>> > problems with guest/QEMU compatibility, in order to placate a
>> > non-functional problem. That is not a good thing.
>>
>> I don't think the suggestion was to disable the existing driver on
>> non-Intel setups, but to add a more generic one. Still, more work to get
>> this actually propagated into guests than doing the change in
>> QEMU. Before I start down that route, I'd like to know whether the issue
>> is actually big enough to make investing time there worth it.
>
> If we're a mmgmt app provisioning a guest, we have to choose what
> watchdog to create - either the old one which works everywhere
> that currently has a driver, or the new one will will work in
> far fewer places. We'll have to wire up guest OS info about
> watchdogs into osinfo, and then wire up all the mgmt apps to
> query this and take action based off it. All possible, but it
> still feels like a huge waste of time to me.
The fact that the device is something emulated and not the Intel
hardware device is actually visible to the guest:
00:02.0 System peripheral: Intel Corporation 6300ESB Watchdog Timer
Subsystem: Red Hat, Inc. QEMU Virtual Machine
Flags: fast devsel
Memory at 10804000 (32-bit, non-prefetchable) [size=16]
Kernel driver in use: i6300ESB timer
Kernel modules: i6300esb
(lspci -v so unfortunately not immediately obvious, but still)
AFAIK the BSDs do not have a driver for this device at the moment -- and
given what turns up when searching for i6300ESB, someone implementing a
driver is far more likely to pick the exising PCI ID.
Windows would also need some dance according to Yan's mail, for unclear
benefits.
On the whole, I think this is not really worth the hassle, we can simply
keep this device as-is.
