[Qemu-devel] [BUG] ahci -device ide-hd|ide-cd select a bus already in use

[Fabio Fantoni]

I started to test/implement q35 cipset on xen hvm domUs.
I found that ide disks and cdrom don't works with q35 using old qemu 
parameters without -device, this is not a blocking problem.
I tried with new qemu parameters and ahci and the disk works.
When I tried to add more that one ahci disk/cdrom devices qemu gave this 
error:
> qemu-system-i386: -device ide-cd,drive=drive-sata-disk1,id=sata1: 
> Can't create IDE unit 1, bus supports only 1 units
> qemu-system-i386: -device ide-cd,drive=drive-sata-disk1,id=sata1: 
> Device initialization failed.
> qemu-system-i386: -device ide-cd,drive=drive-sata-disk1,id=sata1: 
> Device 'ide-cd' could not be initialized
I used qemu 1.6.1 for the test and searching online I found the same 
problem was reported also on fedora, ubuntu and red hat bugtrackers.
Looking for the solution on qemu-devel and git I found this patch:
http://git.qemu.org/?p=qemu.git;a=commit;h=0ee20e665840d8a887c145b368ee121cb86a028e
It is applied on qemu 1.6 but it seems it doesn't solve the problem of 
the selection of full bus but it only show an error when it happens.
Xen with old qemu parameters use index instead of bus and unit but it 
seems missing if I try to use it on -device.
I also read docs/qdev-device-use.txt but it doesn't mention index with 
new -device ide-hd|ide-cd parameters and I found nothing about if=none 
or any ahci disks informations, I think that this document needs to be 
updated/improved.

Thanks for any reply.