Re: scsi passthrough differs between guests

Greetings Peter, > Sent: Thursday, October 15, 2020 at 2:01 PM > From: "Peter Krempa" <pkrempa(a)redhat.com&gt; > To: "daggs" <daggs(a)gmx.com&gt; > Cc: "libvirt-usersredhat.com" <libvirt-users(a)redhat.com&gt; > Subject: Re: scsi passthrough differs between guests > > [...] > > > -drive file=/dev/sg5,if=none,format=raw,id=drive-hostdev0,readonly=on \ > > -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-hostdev0,id=hostdev0 \ > > [...] > > > the bad one: > > /usr/bin/qemu-system-x86_64 \ > > [...] > > > -blockdev '{"driver":"host_device","filename":"/dev/sg0","node-name":"libvirt-hostdev0-backend","read-only":true}' \ > > -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=libvirt-hostdev0-backend,id=hostdev0 \ > > This doesn't corelate with the version numbers you've mentioned, because > the "new" syntax which uses -blockdev was present both in 6.7.0 and > 6.8.0. the "good" syntax was created with libvirt of version which is earlier than 6.7, libvirt was upgraded several times since the vm creation. I don't know if the syntax is changed every version or not.

> Anyways the problem is almost certainly that the hostdev code doesn't > detect that it's a cdrom. We have such a hack in the disk code which > turns a 'host_device' into a 'host_cdrom'. I'll try fixing it but I > don't have a machine with a cdrom handy, so it would be nice if you > could test it afterwards. > > Thanks for the report. > > my system is gentoo, hence, every pkg is compiled, if you provide a patch, I can test it easily.