Hi Elliott,
On 22/08/2025 21:09, Elliott Mitchell wrote:
Since you're not pointing to anything definite, could it be everything
has been resolved?
Unfortunately, the situation has not changed since your last thread
about enabling CONFIG_ACPI=y a couple of years ago. The main feature we
are lacking is the parsing the IORT (used to discover SMMUs and MSI
controllers). Without this...
We've got at least two people for whom ACPI on ARM
works pretty well.
... Xen will only properly boot on "simple" case like the Raspberry PI.
Also, IIRC Xen would use ACPI rather than Device-Tree by default.
There may be many more using it. Perhaps this
should even be done on the 4.20 branch given how long this has been
working?
I am guessing you mean 4.21 which will be released in a couple of months
time, correct?
We have been discussing among the committers on whether we are ok to
enable ACPI despite the fact it is still not feature complete (see
above). The discussion is not fully finalized but if we were to enable
CONFIG_ACPI=y by default then I think we would need the following:
* Select device-tree by default rather than ACPI
* Go through SUPPORT.MD and check what features we marked as
SUPPORTED.md but doesn't work on ACPI.
Maybe you can help with that?
Out of interest, sorry if this was already mentioned before, is there
any reason ACPI is used on the Raspberry PI over Device-Tree? Is there
any issue with the latter on Xen?
The one remaining major issue was the state of EFI-FB support. There
was a patch which had that working for Linux kernel 5.10, but that might
need more work for a proper solution.
Yes. And there was no interest from the other members to fix it
properly. So I gave up that on that work as I don't have a particular
interest of using FrameBuffer on the raspberry PI. Feel free to revive
it and I would be happy to review them.
Cheers,
--
Julien Grall
