On 22/10/2020 09:55, Masami Hiramatsu wrote:
Hi Julien,
Hi Masami,
2020年10月22日(木) 17:11 Julien Grall julien@xen.org:
On 22/10/2020 08:09, Masami Hiramatsu wrote:
Hi,
Hi,
Now I'm trying to use vhost-user-gpu.
I built qemu and xen and installed user /usr/local/. Xen installed it's qemu in /usr/local/lib/xen/bin, Qemu was installed in /usr/local/bin, so those are not conflict.
If I added device_model_args= option to the domU.conf file, it didn't work (failed to exec qemu).
What is the path used for QEMU?
It should be /usr/local/lib/xen/bin/qemu-system-i386, because I replaced it with a wrapper shell script to record the parameters :)
With the device_model_override, I used locally installed /usr/local/bin/qemu-system-i386.
I also added device_model_override= but it didn't change neither. But in both cases, it seems vhost-user-gpu got access from qemu.
To clarify what argument passed to the qemu, I hacked /usr/local/lib/xen/bin/qemu-system-i386, and found that the arguments passed via device_model_args=[] were just added to the original arguments.
OK, now I'm trying to test the qemu-system-i386 itself as below
mhiramat@develbox:/opt/agl$ sudo /usr/local/lib/xen/bin/qemu-system-i386.bin -xen-domid 11 -no-shutdown -chardev socket,id=libxl-cmd,path=/var/run/xen/qmp-libxl-11,server,nowait -mon chardev=libxl-cmd,mode=control -chardev socket,id=libxenstat-cmd,path=/var/run/xen/qmp-libxenstat-11,server,nowait -mon chardev=libxenstat-cmd,mode=control -nodefaults -no-user-config -xen-attach -name agldemo -vnc none -display none -nographic -object memory-backend-file,id=mem,size=512M,mem-path=/dev/shm,share=on -numa node,memdev=mem -chardev socket,path=/opt/agl/vgpu.sock,id=vgpu -device vhost-user-gpu-pci,chardev=vgpu -machine xenpv -m 513
I am a bit confused what you are trying to do. QEMU has to be started after the domain is created by the toolstack (aka xl).
Can you describe a bit more the steps you are using?
This command is solely executed without xl, because I would like to check what error happens. With xl, I just got the errors below.
libxl: error: libxl_exec.c:434:spawn_middle_death: domain 14 device model [20073]: unexpectedly exited with exit status 0, when we were waiting for it to confirm startup libxl: error: libxl_dm.c:3102:device_model_spawn_outcome: Domain 14:domain 14 device model: spawn failed (rc=-3) libxl: error: libxl_dm.c:3322:device_model_postconfig_done: Domain 14:Post DM startup configs failed, rc=-3 libxl: error: libxl_create.c:1836:domcreate_devmodel_started: Domain 14:device model did not start: -3 libxl: error: libxl_aoutils.c:646:libxl__kill_xs_path: Device Model already exited libxl: error: libxl_domain.c:1182:libxl__destroy_domid: Domain 14:Non-existant domain libxl: error: libxl_domain.c:1136:domain_destroy_callback: Domain 14:Unable to destroy guest libxl: error: libxl_domain.c:1063:domain_destroy_cb: Domain 14:Destruction of domain failed
Is there any way to get the qemu's error output?
IIRC the qemu's log should be in /var/log/xen/*. As you have a wrapper shell script, you may be able to re-direct them somewhere different if you can't find them.
qemu-system-i386.bin: -object memory-backend-file,id=mem,size=512M,mem-path=/dev/shm,share=on: -mem-path not supported with Xen
If I use the qemu in xen, it doesn't support -mem-path option. Hmm, memory backend support is not enabled?
This is expected. QEMU is only providing emulated/PV device for Xen guest. The memory management is done by Xen itself. When QEMU requires to access the guest memory, then it will have to issue an hypercall.
I got it. That is the most different point from KVM. (I'm not sure Xen can overcommit memory for the domains)
Xen doesn't support overcommitting memory.
[...]
I'm using the Xen and Qemu master branch, just add a fix for uninstall error on Xen.
I am afraid this is not going to be enough to test virtio on Xen on Arm. For Xen, you would at least need [1].
For QEMU, I don't think you would be able to use qemu i386 because it is going to expose x86 device. You most likely going to need to enable Xen for qemu arm and create a new machine that would match Xen layout.
Cheers,
[1] IOREQ feature (+ virtio-mmio) on Arm