Re: [Xen-devel] [RFC] Virtual disk configuration, PV vs. emulated, backward compatibility etc

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Stefano Stabellini writes ("Re: [Xen-devel] [RFC] Virtual disk configuration, 
PV vs. emulated, backward compatibility etc"):
> On Thu, 29 Jul 2010, Ian Jackson wrote:
> > What if the domain has real sd* devices too ?  (pvscsi, pvusb + usb
> > mass storage, passthrough, ...)
> 
> Clashes are theoretically possible but very hard to produce in practice.
> We are "stealing" device names only for emulated IDE and SCSI disks, and
> emulated SCSI disks don't even work at the moment. So you would need to
> passthrough an IDE controller whose disks are configured as hd* (most
> distros use sd* for IDE disks).

There are definitely people who are using emulated scsi disks; perhaps
they just haven't updated yet.

> I think we are doing exactly what the user asked us to: setting up an
> hdX device; in these very unlikely scenarios the user knows what he is
> doing and can change the configuration.

Well, no, they can't, because their bootloader probably doesn't
understand anything besides what they're actually using.

Certainly stealing the major number for scsi disks seems quite
dangerous.  pv-usb is hardly that unlikely a scenario.

Ian.

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