kata 9p

Manually, using qemu-kvm command line

There are a nice set of details on the QEMU wiki describing this, so this section will be quite short. To share host files w/ the guest, we use 9p over virtio in conjunction w/ a filesystem device exporting the portion of the host filesystem that we'd like to share with the guest.

# /usr/bin/qemu-kvm -m 1024 -name f15 -drive file=/images/f15.img,if=virtio
-fsdev local,security_model=passthrough,id=fsdev0,path=/tmp/share -device virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=hostshare

This tells qemu to create a 9pvirtio device exposing the mount_tag hostshare (just a name to identify the mount point). That device is coupled to an fsdev named fsdev0, which specifies which portion of the host filesystem we are sharing, and in which mode (see QEMU wiki for details on the security models).

Now, in the guest we need to mount the 9p filesystem from the host using the virtio transport. The mount_tag is used to identify the host's share.

# mkdir /tmp/host_files
# mount -t 9p -o trans=virtio,version=9p2000.L hostshare /tmp/host_files

That's it...now we can read/write files in that directory from either the host or the guest.

root@(none):/# mount -t 9p -o trans=virtio,version=9p2000.L kataShared tmp
root@(none):/# ls
bin dev home lost+found mnt proc run srv tmp var
boot etc lib media opt root sbin sys usr
root@(none):/# ls /tmp/
hello.txt
root@(none):/#

root@(none):/# ls
bin   dev  home  lost+found  mnt  proc  run   srv  tmp  var
boot  etc  lib   media       opt  root  sbin  sys  usr
root@(none):/# mkdir kata1
mkdir: cannot create directory 'kata1': Read-only file system
root@(none):/# cd run/
root@(none):/run# ls
lock  systemd  utmp
root@(none):/run# mkdir kata1
mkdir: cannot create directory 'kata1': Read-only file system
root@(none):/run# ls
lock  systemd  utmp
root@(none):/run# 

-device virtio-9p-pci,disable-modern=false,fsdev=fsdev0,mount_tag=label1,romfile=: 9pfs device couldn't find fsdev with the id = fsdev0

 原来是fsdev=fsdev0 和id=label1不一致

 -device virtio-9p-pci,disable-modern=false,fsdev=fsdev0,mount_tag=label1,romfile= 
        -fsdev local,id=label1,path=share1,security_model=none 

改成这个就可以哦

   -device virtio-9p-pci,disable-modern=false,fsdev=fsdev0,mount_tag=label1,romfile= 
        -fsdev local,id=fsdev0,path=share1,security_model=none 

> sudo qemu-kvm --no-kvm -m 1024 -kernel
> /mnt/test/usr/src/linux-3.13-rc1/arch/x86/boot/bzImage -append
> 'root=/dev/root rootfstype=9p rootflags=trans=virtio,version=9p2000.L ro
> console=ttyS0' -serial stdio -fsdev
> local,id=root,path=/mnt/test,security_model=none -device
> virtio-9p-pci,fsdev=root,mount_tag=/dev/root

#  mkdir -p /mnt/host
#  mount -t 9p -o trans=virtio host /mnt/host
9pnet_virtio: no channels available for device host
mount: mounting host on /mnt/host failed: No such file or directory
# ls -al /mnt
total 0
drwxr-xr-x    3 root     root            60 May 29 08:04 .
drwxr-xr-x   18 root     root           420 May 29 08:02 ..
drwxr-xr-x    2 root     root            40 May 29 08:04 host
# 

挂多个

root@(none):/var# ls
backups lib local lock mail opt run spool tmp
root@(none):/var# mount -t 9p -o trans=virtio label1 opt
root@(none):/var# mount -t 9p -o trans=virtio kataShared tmp
root@(none):/var# ls opt/
kata.txt
root@(none):/var# ls tmp/
hello.txt
root@(none):/var# cat opt/kata.txt
hello3
root@(none):/var# cat tmp/hello.txt
kata1
root@(none):/var#