Re: CXL emulation on aarch64

[Itaru Kitayama]

> On Jan 16, 2025, at 19:58, Jonathan Cameron <Jonathan.Cameron@huawei.com> 
> wrote:
> 
> On Thu, 16 Jan 2025 15:04:53 +0900
> Itaru Kitayama <itaru.kitayama@linux.dev> wrote:
> 
>> 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.
> 
> Always use the latest dated branch on that tree.  I release whenever there
> is something new to carry or a major rebase needed.
> 
> cxl-<date> is the right branch to use. Hope that helps.

When do you think you want to get them (aarch64 specific?) merged mainline. Any 
reason you want to carry the patches by yourself?

Itaru.

> 
> Jonathan
> 
>> 
>> 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