block: Fix virtual media change for if=none

BlockDriverState member removable controls whether virtual media
change (monitor commands change, eject) is allowed.  It is set when
the "type hint" is BDRV_TYPE_CDROM or BDRV_TYPE_FLOPPY.

The type hint is only set by drive_init().  It sets BDRV_TYPE_FLOPPY
for if=floppy.  It sets BDRV_TYPE_CDROM for media=cdrom and if=ide,
scsi, xen, or none.

if=ide and if=scsi work, because the type hint makes it a CD-ROM.
if=xen likewise, I think.

For the same reason, if=none works when it's used by ide-drive or
scsi-disk.  For other guest devices, there are problems:

* fdc: you can't change virtual media

    $ qemu [...] -drive if=none,id=foo,... -global isa-fdc.driveA=foo
    QEMU 0.12.50 monitor - type 'help' for more information
    (qemu) eject foo
    Device 'foo' is not removable

  unless you add media=cdrom, but that makes it readonly.

* virtio: if you add media=cdrom, you can change virtual media.  If
  you eject, the guest gets I/O errors.  If you change, the guest sees
  the drive's contents suddenly change.

* scsi-generic: if you add media=cdrom, you can change virtual media.
  I didn't test what that does to the guest or the physical device,
  but it can't be pretty.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/hw/fdc.c b/hw/fdc.c
index 1496cfa14..6c748782e 100644
--- a/hw/fdc.c
+++ b/hw/fdc.c
@@ -1847,10 +1847,16 @@ static void fdctrl_result_timer(void *opaque)
 static void fdctrl_connect_drives(FDCtrl *fdctrl)
 {
     unsigned int i;
+    FDrive *drive;
 
     for (i = 0; i < MAX_FD; i++) {
-        fd_init(&fdctrl->drives[i]);
-        fd_revalidate(&fdctrl->drives[i]);
+        drive = &fdctrl->drives[i];
+
+        fd_init(drive);
+        fd_revalidate(drive);
+        if (drive->bs) {
+            bdrv_set_removable(drive->bs, 1);
+        }
     }
 }