[Qemu-block] [PATCH v2 for-2.4 3/3] hw/arm/virt: Make block devices default to virtio

[Peter Maydell]

Now we have virtio-pci, we can make the virt board's default block
device type be IF_VIRTIO. This allows users to use simplified
command lines that don't have to explicitly create virtio-pci-blk
devices; the -hda &c very short options now also work.

This means we also need to set no_cdrom to avoid getting a
default cdrom device -- this is needed because the virtio-blk
device will fail if it is connected to a block backend with
no media, which is what the default cdrom device typically is.
Providing a cdrom with media via -cdrom will still work.

Note that this change means that some command lines which used
to work (by accident) will stop working. Where a drive was connected
manually to a device but without 'if=none' being specified, we
used to treat this as an IDE drive, which we would then not autoplug
because the board doesn't support IDE. Now we will treat it as a
virtio disk and autoplug it, which means the attempt to use the
drive manually will fail:
  qemu-system-arm: -drive file=img.qcow2,id=foo: Drive 'foo' is already
  in use because it has been automatically connected to another device
  (did you need 'if=none' in the drive options?)
The command line will be changed to include 'if=none', as the
error message suggests.

Signed-off-by: Peter Maydell <address@hidden>
---
 hw/arm/virt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index f1e85c8..7e643ba 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -966,6 +966,8 @@ static void virt_class_init(ObjectClass *oc, void *data)
     mc->init = machvirt_init;
     mc->max_cpus = 8;
     mc->has_dynamic_sysbus = true;
+    mc->block_default_type = IF_VIRTIO;
+    mc->no_cdrom = 1;
 }
 
 static const TypeInfo machvirt_info = {
-- 
1.9.1