On Mon, Aug 16, 2010 at 01:46:13PM +0100, Richard W.M. Jones wrote:
On Mon, Aug 16, 2010 at 07:21:12PM +0800, Jin Xin Zheng wrote:
On 08/16/2010 06:40 PM, Richard W.M. Jones wrote:
The virtual cdrom device in qemu will be readonly (is that right?).
Then how are you going to tune the boot process as I know it would require writing to the filesystem. I'm not aware of us needing to write to the root filesystem during boot (well, there is one place where we do 'mkdir -p /sysroot' but
On Mon, Aug 16, 2010 at 10:17:30AM +0800, Jin Xin Zheng wrote: that can be fixed).
However there is an issue that we modify configuration files in the daemon, in particular /etc/lvm/lvm.conf, which would require either making this directory a tmpfs or using some other method to make root writable.
Rich.
Are you sure all the binary utils inside the appliance will not write logging files when running?
I guess we can mount /tmp, /var and maybe a few other things as tmpfs?
In fact when I saw this the first thing came up to my head was that our modified source for doing gcov -- we could collect the .gcda files in the build directory after libguestfs was invoked. But the guestfsd which runs inside the appliance produces the .gcda files in the temp ramfs. We have made a pretty lot of effort in order to tar-out these files before the subprocess was killed.
If the filesystem is readonly then I'll have to do more to allow guestfsd to write debugging coverage info into a writable place. However this is not a problem for libguestfs, it's just a problem for me...
The alternative is to use a regular drive (not a CD), and attach it using:
-drive file=isofile,snapshot=on
Since this will be one of the drives, it has two disadvantages: we need to work a little bit harder to hide this drive from users, and it reduces the number of drives available to users from 26 to 25 (assuming drives can only be named /dev/[hsv]d[a-z], which is true of a lot of daemon code at the moment).
I don't know the internals of libguestfs that well, but is filtering out a harddisk really more trouble than filtering out a CDROM ? Any IDE/SATA CDROM device will appear as /dev/[hsv]d[a-z] too, even if it has a /dev/cdrom link. So AFAICT you need todo the same kind of filtering for either disks or cdroms, and you loose 1 drive letter in both cases :-( Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|