Re: [Xen-devel] Greater than 16 xvd devices for blkfront

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

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

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