Re: CXL emulation on aarch64

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

On Tue, 14 Jan 2025 12:03:03 +0900
Itaru Kitayama <itaru.kitayama@linux.dev> wrote:

> Hi Jonathan, 
> 
> > On Jan 10, 2025, at 21:31, Jonathan Cameron <Jonathan.Cameron@huawei.com> wrote:
> > 
> > On Fri, 10 Jan 2025 09:20:54 +0000
> > "Zhijian Li (Fujitsu)" via <qemu-devel@nongnu.org> wrote:
> >   
> >> On 10/01/2025 13:29, Itaru Kitayama wrote:  
> >>> Hi,
> >>> Is anybody working on the CXL emulation on aarch64?    
> >> 
> >> I'm not currently working on the CXL emulation on aarch64.
> >> 
> >> However, IIRC the CXL maintainer's tree should work.
> >> https://gitlab.com/jic23/qemu/  
> > 
> > Pick up latest branch from there. I'm prepping a rebased version
> > with some new stuff but might take a few more days.  
> 
> Thanks for sharing your work with us.  Your master and cxl-2024-11-27 branches give:
> 
> $ qemu-system-aarch64: -accel tcg,cxl=on: Property 'tcg-accel.cxl' not found

cxl is a machine property not a accel one. So needs to be after virt
There are tests in the tree for bios tables. Copy the command line from those.

> 
> My commands are below:
> $HOME/projects/qemu/build/qemu-system-aarch64 \
>         -M virt,virtualization=on,gic-version=3 \
>         -M acpi=off -cpu max,sme=off -m 8G -smp 4 \
>         -accel tcg,cxl=on \
>         -nographic \
>         -bios $HOME/cca-v4/out/bin/flash.bin \
>         -kernel Image-cca \
>         -drive format=raw,if=none,file=$HOME/cca-v4/out-or/images/rootfs.ext2,id=hd0 \
>         -device virtio-blk-pci,drive=hd0 \
>         -append root=/dev/vda \
>         -nodefaults \
>         --serial tcp:localhost:54320 \
>          -serial tcp:localhost:54321 \
>          -append "root=/dev/vda earlycon console=hvc0" \
>          -device virtio-net-pci,netdev=net0 \
>          -netdev user,id=net0 \
>          -device virtio-9p-device,fsdev=shr0,mount_tag=shr0 \
>          -fsdev local,security_model=none,path=../../,id=shr0
> 
> Yes, I’m using Linaro’s CCA capable OP-TEE builds above.

I'm a little curious why optee is relevant for this but shouldn't matter as long
as an appropriate EDK2 is loaded.

Jonathan

> 
> Let me know which branch you were suggesting.
> 
> Thanks,
> Itaru. 
> 
> > 
> > Note my main development work is on arm64 so that tends to work
> > more reliably than x86 which I only lightly test for stuff that
> > isn't ready for upstream yet.
> > 
> > Give me a shout if you run into any problems.
> > 
> > The main blocker on upstreaming this is resolving the missing device tree
> > support for PCI expander bridges.  I've not made any progress on this since
> > talk at Linaro connect in 2023.
> > 
> > Jonathan
> > 
> >   
> >> 
> >> 
> >> Thanks
> >> Zhijian
> >>   
> >>> If there’s a WIP branch, a pointer would be appreciated.
> >>> 
> >>> Itaru    
> >   
>