Michael Tokarev <address@hidden> writes:
10.06.2014 10:34, Paolo Bonzini wrote:
Il 10/06/2014 08:30, Michael Tokarev ha scritto:
Hello.
The question is: are the drive shortcuts - -cdrom, -hda, -hdb etc -
supposed to work in -machine q35 too? Or are they merely ignored?
qemu-system-x86_64 -machine q35 -cdrom foo.img
[]
It should work. I remember some complications due to AHCI not
having slaves, but it is a bug.
It looks like the "short" -drive if=ide option does not connect the
created drive to any bus at all. With the above command, or with
-drive if=ide,index=*,bus=*, info qtree does not show the drive at
all. While -drive if=none,id=X -device ide-cd,drive=X connects the
drive to the right bus just fine.
-drive mixes up configuration of backend and frontend (a.k.a. device
model), as follows:
1. It always defines a backend. "info block" shows them.
2. It always defines a few frontend configuration bits for the device
models to pick up.
3. Except with if=none, it posts a request to board code to create a
suitable frontend. It's up to the board code to honor, reject or
ignore the request. The i440FX boards honor it, the Q35 boards
ignore it.
Nobody has gotten around to making the Q35 boards honor it, in part
because there has been some confusion on what if=ide is supposed to
mean on Q35. Should it connect an ide-hd / ide-cd in SATA mode or in
legacy PATA mode?
I've always argued for SATA, because for me if=ide does *not* imply a
specific kind of HBA any more than if=scsi does, and the "natural"
HBA for Q35 is AHCI in SATA mode.
Kevin (cc'ed) has argued for a way to make it connect in legacy PATA
mode. I'd be fine with that, as long as it's off by default.
Patches welcome.