Comment # 9 on bug 954452 from Robert Milasan

(In reply to Olaf Hering from comment #8)
> The strings for a given block device are "free strings", that means a given
> block driver is free to pick any name. It just happend that IDE used to pick
> hd, SCSI picked "sd" and so on. In the early days the PV drivers used to
> claim the well known names and their major:minors to make it easier to
> install and run existing distros.

Not really, the device name is given based on what layer is used, for example
SCSI/SATA/ATA usually can go thru SCSI or libata (I'm talking about kernel) and
their naming will start with 'sd'.

Xen has its own things and will be something like 'xvd', but you have 'hd'
because you have a bit of a different setup, maybe not using Xen's own driver
or layer or something, but the kernel and kernel sees it as an old device.

I really dont know enough about Xen to comment too much.
Here you are emulating an old machine, somehow.

> 
> Today the names can be still passed into the guest. For some reason I picked
> "hd" instead of "xvd" for my PV guests. So that part might be fixeable by
> adjusting both the domU.cfg and also the used devicenames within the VM. In
> the end I would call this a regression. "hd" per se has no relationship to
> IDE hardware anymore, as explained above. Please restore "hd" support, I'm
> sure such names are in use.
> 
> Not sure why the HVM guest fails. Here the "hd" in domU.cfg has additional
> meaning, it tells qemu to create an emulated IDE controller which is later
> driven by the SATA drivers. Have to see how to debug this.

'hd' is not really is use, because is not possible. A normal machine that is
64bit wont be using IDE, is too old.

At least is what I know.