Re: CXL emulation on aarch64

[Itaru Kitayama]

Hi Jonathan,

> On Jan 14, 2025, at 19:26, Jonathan Cameron <Jonathan.Cameron@huawei.com> 
> wrote:
> 
> 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.
> 

I picked up your tree’s “master” and “cxl-next” as of today, and only the 
latter at least booted.
The former gives:

qemu-system-aarch64: Property 'virt-9.2-machine.cxl' not found

Should I stick with the cxl-next? My concern is that the base QEMU version is a 
bit old
7.0.50.

Thanks,
Itaru.

> 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