Re: [libvirt] [PATCH V9 3/3] Add support for file descriptor sets

On 03/07/2013 11:14 AM, Stefan Berger wrote: > Add support for file descriptor sets by converting some of the > command line parameters to use /dev/fdset/%d if -add-fd is found > to be supported by QEMU. For those devices libvirt now open()s > the device to obtain the file descriptor and 'transfers' the > fd using virCommand. > > For the following fragments of domain XML > > > <disk type='file' device='disk'> > <driver name='qemu' type='raw'/> > <source file='/var/lib/libvirt/images/fc14-x86_64.img'/> > <target dev='hda' bus='ide'/> > <address type='drive' controller='0' bus='0' target='0' unit='0'/> > </disk> Discussion on the qemu list has made it obvious that we want this for NFS-mounted images, but maybe not for local images or on other file systems that actually support SELinux labeling (after all, the point of fd passing is not to move DAC checking out of the kernel and into user-space libvirtd, but to make up for lack of SELinux labeling on NFS). Still, we are waiting for a qemu solution on how to do fd passing for backing files (the so-called -blockdev design), which means that for now, the best we could do with the selinux bool virt_use_nfs disabled is support only flat images (no backing file, no creation of snapshots).