projects / qemu.git / blame
| Commit | Line | Data |
|---|---|---|
| 0f58f68b GH |
1 | |
| 2 | qemu usb storage emulation | |
| 3 | -------------------------- | |
| 4 | ||
| 34707333 | 5 | QEMU has three devices for usb storage emulation. |
| 0f58f68b GH |
6 | |
| 7 | Number one emulates the classic bulk-only transport protocol which is | |
| 085d8134 | 8 | used by 99% of the usb sticks on the market today and is called |
| 0f58f68b GH |
9 | "usb-storage". Usage (hooking up to xhci, other host controllers work |
| 10 | too): | |
| 11 | ||
| 12 | qemu ${other_vm_args} \ | |
| 13 | -drive if=none,id=stick,file=/path/to/file.img \ | |
| 14 | -device nec-usb-xhci,id=xhci \ | |
| 15 | -device usb-storage,bus=xhci.0,drive=stick | |
| 16 | ||
| 17 | ||
| 18 | Number two is the newer usb attached scsi transport. This one doesn't | |
| 19 | automagically create a scsi disk, so you have to explicitly attach one | |
| 20 | manually. Multiple logical units are supported. Here is an example | |
| 21 | with tree logical units: | |
| 22 | ||
| 23 | qemu ${other_vm_args} \ | |
| 24 | -drive if=none,id=uas-disk1,file=/path/to/file1.img \ | |
| 25 | -drive if=none,id=uas-disk2,file=/path/to/file2.img \ | |
| 26 | -drive if=none,id=uas-cdrom,media=cdrom,file=/path/to/image.iso \ | |
| 27 | -device nec-usb-xhci,id=xhci \ | |
| 28 | -device usb-uas,id=uas,bus=xhci.0 \ | |
| 29 | -device scsi-hd,bus=uas.0,scsi-id=0,lun=0,drive=uas-disk1 \ | |
| 30 | -device scsi-hd,bus=uas.0,scsi-id=0,lun=1,drive=uas-disk2 \ | |
| 31 | -device scsi-cd,bus=uas.0,scsi-id=0,lun=5,drive=uas-cdrom | |
| 32 | ||
| 33 | ||
| 34707333 GH |
34 | Number three emulates the classic bulk-only transport protocol too. |
| 35 | It's called "usb-bot". It shares most code with "usb-storage", and | |
| 36 | the guest will not be able to see the difference. The qemu command | |
| dfaba10b | 37 | line interface is similar to usb-uas though, i.e. no automatic scsi |
| 34707333 | 38 | disk creation. It also features support for up to 16 LUNs. The LUN |
| 085d8134 | 39 | numbers must be continuous, i.e. for three devices you must use 0+1+2. |
| 34707333 GH |
40 | The 0+1+5 numbering from the "usb-uas" example isn't going to work |
| 41 | with "usb-bot". | |
| 42 | ||
| b91e0139 GH |
43 | Starting with qemu version 2.7 usb-bot and usb-uas devices can be |
| 44 | hotplugged. In the hotplug case they are added with "attached = | |
| 45 | false" so the guest will not see the device until the "attached" | |
| 46 | property is explicitly set to true. That allows to attach one or more | |
| 47 | scsi devices before making the device visible to the guest, i.e. the | |
| 48 | workflow looks like this: | |
| 49 | ||
| 50 | (1) device-add usb-bot,id=foo | |
| 51 | (2) device-add scsi-{hd,cd},bus=foo.0,lun=0 | |
| 52 | (2b) optionally add more devices (luns 1 ... 15). | |
| 53 | (3) scripts/qmp/qom-set foo.attached = true | |
| 54 | ||
| 0f58f68b GH |
55 | enjoy, |
| 56 | Gerd | |
| 57 | ||
| 58 | -- | |
| 59 | Gerd Hoffmann <[email protected]> |