Re: [PATCH] blockdev: add 'media=cdrom' argument to support usb cdrom emulated as cdrom

[Zhipeng Lu]

libvirt issue： https://gitlab.com/libvirt/libvirt/-/issues/261

1、start vm with usb cdrom
<disk type="file" device="cdrom">
  <driver name="qemu" type="raw" discard="unmap"/>
  <source file="/tmp/cdrom"/>
  <target dev="sda" bus="usb"/>
  <readonly/>
  <address type="usb" bus="0" port="1"/>
</disk>

2、 get qemu cmdline


qemu     ... -blockdev 
{"driver":"file","filename":"/tmp/cdrom","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"} 
-blockdev 
{"node-name":"libvirt-1-format","read-only":true,"discard":"unmap","driver":"raw","file":"libvirt-1-storage"} 
-device 
{"driver":"usb-storage","bus":"usb.0","port":"1","drive":"libvirt-1-format","id":"usb-disk0","removable":false}
3、 in vm

NAME          MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda             8:0    0  100M  1 disk
vda           252:0    0   10G  0 disk
├─vda1        252:1    0    1G  0 part /boot
└─vda2        252:2    0    9G  0 part
  ├─rhel-root 253:0    0    8G  0 lvm  /
  └─rhel-swap 253:1    0    1G  0 lvm  [SWAP]
lshw -short|grep cdrom -i
No cdrom.

My patch is to solve this problem, usb cdrom emulated as cdrom.



在 2022/12/1 23:35, Markus Armbruster 写道:
> luzhipeng <luzhipeng@cestc.cn> writes:
>
> > From: zhipeng Lu <luzhipeng@cestc.cn>
> >
> > The drive interface supports media=cdrom so that the usb cdrom
> > can be emulated as cdrom in qemu, but libvirt deprived the drive
> > interface, so media=cdrom is added to the blockdev interface to
> > support usb cdrom emulated as cdrom
> >
> > Signed-off-by: zhipeng Lu <luzhipeng@cestc.cn>
>
> What problem are you trying to solve?