Re: Greater than 16 xvd devices for blkfront

[Jeremy Fitzhardinge <jeremy@goop.org>]

Chris Wright wrote:
> Well, we don't actually need 202, or any minor numbers at all.  The major
> is only needed for the case where xvd masquerades as IDE or SCSI.
> We ripped this wart out for upstream Linux. 

I'm considering putting it back in if it makes anyone's life easier.  In 
general using labels/uuids is the best way to make an installation 
device-agnostic, but installers might have an easier time with a forged 
scsi device or something.  I mentioned it in passing to Al Viro, and he 
was surprisingly non-insulting about the notion.

>  And the guest can happily
> dynamically allocate minor numbers on its own behalf.  A disk discovery
> event can be completely dynamic, the admin just wouldn't be able to
> guarantee which minor slot gets allocated for a particular disk in
> a guest.  We do have mount by label or UUID.
>   

That's true for filesystems which have already been initialized.  But if 
you're attaching 4 new devices to a guest and they appear at random 
device nodes, how do you know which is which?  Smell?

    J