Hi Xiaodong, On Mon, Oct 11, 2021 at 3:32 PM Liuxiangdong <liuxiangdong5@xxxxxxxxxx> wrote: > > Hi, Yongji. > > I tried vduse with null-blk: > > $ qemu-storage-daemon \ > --chardev socket,id=charmonitor,path=/tmp/qmp.sock,server,nowait \ > --monitor chardev=charmonitor \ > --blockdev > driver=host_device,cache.direct=on,aio=native,filename=/dev/nullb0,node-name=disk0 > \ > --export > type=vduse-blk,id=test,node-name=disk0,writable=on,name=vduse-null,num-queues=16,queue-size=128 > > The qemu-storage-daemon is yours > (https://github.com/bytedance/qemu/tree/vduse) > > And then, how can we use this vduse-null (dev/vduse/vduse-null) in vm(QEMU)? > Then we need to attach this device to vdpa bus via vdpa tool [1]: # vdpa dev add vduse-null mgmtdev vduse With the virtio-vdpa module loaded, we will see the block device in host. And if we'd like to use it in a VM, we need to load the vhost-vdpa module (a /dev/vhost-vdpa-0 char device will be presented) and build a new qemu binary with the source code in https://github.com/bytedance/qemu/tree/vhost-vdpa-blk. Then we can use the below command line to start a VM with the vhost-vdpa-blk device: ./qemu-system-x86_64 -M pc -cpu host --enable-kvm -smp 8 \ -m 4G -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on \ -numa node,memdev=mem -monitor vc -serial stdio -no-user-config -nodefaults \ -vnc 0.0.0.0:1 -k en-us -vga cirrus \ -device vhost-vdpa-blk-pci,num-queues=1,vdpa-dev=/dev/vhost-vdpa-0 [1] https://man7.org/linux/man-pages/man8/vdpa-dev.8.html Thanks, Yongji
