Re: A confusion about CXL in arm virt machine

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Mon, 18 Sep 2023 13:41:20 +0100
Peter Maydell <peter.maydell@linaro.org> wrote:

> On Mon, 19 Jun 2023 at 10:58, Jonathan Cameron via <qemu-arm@nongnu.org> wrote:
> >
> > On Fri, 16 Jun 2023 14:10:24 -0400
> > Gregory Price <gregory.price@memverge.com> wrote:  
> > >
> > > Last I tested cxl-2023-05-25 branch of Johnathan's fork is working on x86:
> > >
> > > https://gitlab.com/jic23/qemu/-/tree/cxl-2023-05-25
> > >
> > > I have not worked with the ARM machine, but Johnathan may be able to
> > > comment on the state of ARM support for this code.  
> >
> > ARM support is not yet upstream.  There are some precursor problems we still
> > have to solve because arm-virt should also support device tree bindings.
> > See talk I gave at Linaro connect that includes some of them:
> > https://resources.linaro.org/en/resource/hM986DSHfoTrZ98UjpvLg1
> >
> > For now, I'm carrying the arm-virt + ACPI support on the tree above.
> > There are a lot of things we still need to provide support for in QEMU CXL
> > world so for now figuring out the path forward for upstreaming ARM support
> > isn't at the top of my list.  I'll get back to it at somepoint - probably
> > next month.  
> 
> Is the Arm CXL support still out-of-tree? I ask because at the
> moment docs/system/devices/cxl.rst has some aarch64 virt command
> lines which don't work, and we've had a bug report about it:
> https://gitlab.com/qemu-project/qemu/-/issues/1892

It's still blocked on device tree support...
Step 1 to fixing that is working out that PXB device tree enumeration
dance. I've not yet had time to look at whether we can do
more of the enumeration part in the OS.

> 
> Could you submit a patch to correct the documentation, please
> (either fixing the command line, or just deleting any claims
> to aarch64 support if it's not upstream) ?

Strange, I thought we'd long fixed the docs for this.
Gah, I messed up a rebase of Gregory's series adding multiple
region support and put some back in again.

I'll roll this fix into a little series with some others I have queued up
and post it in a few minutes.

Jonathan





> 
> thanks
> -- PMM
>