Re: Consider changing CONFIG_ACPI default on ARM?

[Grygorii Strashko <grygorii_strashko@xxxxxxxx>]

On 06.08.25 07:30, Elliott Mitchell wrote:
> Sigh, resending as I lost some of the intended Cc targets when originally
> creating the message.  Sorry about the duplication for people who have
> already seen, but I thought this might be worthy of wider discussion.
>
>
>
> I would like to draw the attention of a few people on xen-devel to the
> thread which occured on xen-users recently and quoted below:
>
> https://lists.xenproject.org/archives/html/xen-users/2025-07/msg00001.html
>
> On Tue, Jul 01, 2025 at 10:01:13PM +0200, Paul Leiber wrote:
> > Unfortunately, I don't have a direct answer to the question (as is so often
> > the case, due to my limited knowledge and experience). However, I am
> > successfully running Xen on a RPi 4 (mostly, except for some VLAN related
> > networking issues).
> >
> > I used instructions in [1] to install vanilla Debian on the RPi, including
> > UEFI boot and grub. I then compiled Xen with expert options and ACPI
> > enabled.
> >
> > I don't know if there are better solutions. For example, I suffer from the
> > fact that I2C doesn't work when using UEFI boot on a RPi. Nowadays, Debian
> > provides their own vanilla Debian images for RPi and with working I2C, but
> > these images are using a different boot method that I didn't know how to use
> > with Xen.  So far, the procedure described above seems to be the easiest
> > solution for me.
>
> > [1] https://forums.raspberrypi.com/viewtopic.php?t=282839
> >
> > Am 30.06.2025 um 12:35 schrieb Sumit Semwal:
> > > I've just begun to experiment with the Raspberry Pi 5, trying to run a
> > > simple xen + Dom0 setup, using uBoot, and the bookworm based Rpi
> > > distro.
> > >
> > > I've tried combinations of the following setup:
> > >
> > > 1. prebuilt Rpi5 kernel + dtbs, and have also tried to build them from
> > > source [1]
> > > 2. Xen from upstream [2] and xen-troops [3]
> > > 3. upstream uBoot from [4]
> > >
> > > but with the same result: [short log below; I can provide a fuller log
> > > if needed]
> > >
> > > (XEN) DT: ** translation for device /axi/msi-controller@1000130000 **
> > > (XEN) DT: bus is default (na=2, ns=2) on /axi
> > > (XEN) DT: translating address:<3> 000000ff<3> fffff000<3>
> > > (XEN) DT: parent bus is default (na=2, ns=1) on /
> > > (XEN) DT: walking ranges...
> > > (XEN) DT: default map, cp=0, s=1000000000, da=fffffff000
> > > (XEN) DT: default map, cp=1000000000, s=100000000, da=fffffff000
> > > (XEN) DT: default map, cp=1400000000, s=400000000, da=fffffff000
> > > (XEN) DT: default map, cp=1800000000, s=400000000, da=fffffff000
> > > (XEN) DT: default map, cp=1c00000000, s=400000000, da=fffffff000
> > > (XEN) DT: not found !
> > > (XEN) Unable to retrieve address 1 for /axi/msi-controller@1000130000
> > > (XEN) Device tree generation failed (-22).
> > > (XEN) debugtrace_dump() global buffer starting
> > > 1 cpupool_create(pool=0,sched=6)
> > > 2 Created cpupool 0 with scheduler SMP Credit Scheduler rev2 (credit2)
> > > 3 cpupool_add_domain(dom=0,pool=0) n_dom 1 rc 0
> > > (XEN) wrap: 0
> > > (XEN) debugtrace_dump() global buffer finished
> > > (XEN)
> > > (XEN) ****************************************
> > > (XEN) Panic on CPU 0:
> > > (XEN) Could not set up DOM0 guest OS (rc = -22)
> > > (XEN) ****************************************
> > >
> > >
> > > I'm certain I'm missing something, but before I delve deeper, I just
> > > wanted to ask if this is a known issue, and if so, are there any
> > > workarounds or solutions available for this?
> > >
> > > Any help about this is highly appreciated!
> > >
> > > Thanks and Best regards,
> > > Sumit.
> > >
> > > [1]:  https://github.com/raspberrypi/linux rpi-6.12.y branch
> > > [2]: git://xenbits.xen.org/xen.git - main branch
> > > [3] xen-troops https://github.com/xen-troops/xen - rpi5_dev branch
> > > [4]: https://github.com/u-boot/u-boot.git master branch
> Ultimately Debian is choosing to leave most defaults alone.  So far the
> Xen developers have left CONFIG_ACPI defaulting to off on ARM*.  The
> Debian project doesn't have paid people to support Raspberry PI hardware,
> despite being rather common.  As a result there aren't any official
> Raspberry PI images, but people associated with Tianocore have gotten
> generic images to boot on Raspberry PI hardware.
>
> I'm unsure of the likelihood of getting the Debian maintainers to
> override the default.  Yet due being by far the simplest way to install
> Debian and Xen on a very common ARM64 platform, perhaps the Xen
> developers should consider changing?
Information about our experiments with RPI5 can be found in [1]
and demonstration project [2].

Seen no issues (except no IOMMU as platform is closed and no docs/support).

[1] https://github.com/xen-troops/meta-xt-rpi5/wiki
[2] https://github.com/xen-troops/meta-xt-prod-devel-rpi5

--
Best regards,
-grygorii