Since 2.9 it is possible for a user to care only about nodes and qdev devices, but not about BlockBackends, by defining with -blockdev and using their node name in -device. Devices create an anonymous BlockBackend internally then.
One of the major problems in this setup is that such devices are not listed in query-block or HMP 'info block' because the BBs are not monitor-owned. A recent discussion concluded that we really want to replace query-block and friends with something that matches QEMU's internals better, but there's no way to do that in 2.10 (and I wouldn't bet on it to be completed for 2.11). So for now, just make the devices appear in query-block and add the qdev ID there in order to make the devices identifiable (they have 'device': '' because the BB is anonymous). With the additional qdev field, it turned out that with empty drives, ide-cd and scsi-cd weren't even properly attached to the BlockBackend. If you do it right, this even results in crashes. (Floppy already gets it right, in case you wondered.) After this series, -device drive=<node-name> should be reasonably usable without a major loss of functionality like before. Kevin Wolf (9): block: Make blk_get_attached_dev_id() public block/qapi: Add qdev device name to query-block block: Make blk_all_next() public block/qapi: Use blk_all_next() for query-block block: List anonymous device BBs in query-block ide: bdrv_attach_dev() for empty CD-ROM scsi-disk: bdrv_attach_dev() for empty CD-ROM qemu-iotests: Test 'info block' qemu-iotests: Test unplug of -device without drive block/block-backend.c | 5 +- block/qapi.c | 20 +- hmp.c | 11 +- hw/ide/qdev.c | 3 + hw/scsi/scsi-disk.c | 5 + include/sysemu/block-backend.h | 2 + qapi/block-core.json | 5 +- tests/qemu-iotests/067 | 13 ++ tests/qemu-iotests/067.out | 40 ++++ tests/qemu-iotests/186 | 147 +++++++++++++ tests/qemu-iotests/186.out | 489 +++++++++++++++++++++++++++++++++++++++++ tests/qemu-iotests/group | 1 + 12 files changed, 731 insertions(+), 10 deletions(-) create mode 100755 tests/qemu-iotests/186 create mode 100644 tests/qemu-iotests/186.out -- 1.8.3.1
