Re: [Xen-devel] [PATCH 3 of 5] blkif.h: Add definitions for virtual block device major numbers

["Justin T. Gibbs" <justing@xxxxxxxxxxxxxxxx>]

On Feb 9, 2012, at 8:17 AM, Ian Jackson wrote:

> Justin T. Gibbs writes ("Re: [Xen-devel] [PATCH 3 of 5] blkif.h: Add 
> definitions for virtual block device major numbers"):
>> I wasn't aware of this file.  After a brief look, it seems there is
>> information missing from both vbd-interface.txt and blkif.h.  Per
>> vbd-interface.txt, there is also an error in blkif.h.  The "virtual-device"
>> node must tolerate 32bit integers.
>> 
>> I'll fix the size specification for the "virtual-device" node, but how
>> should I reconcile blkif.h and vbd-interface.txt.  I hate information
>> duplication since one version is invariably stale.
> 
> I wrote vbd-interface.txt and I think it's largely accurate.  I wasn't
> aware of any duplication with blkif.h.  If there are differences then
> we will have to discuss them here I think, or read the code.
> 
> Ian.

I was thinking that the high numbered SCSI disk major numbers
were not covered by vbd-interface.txt.  In looking more closely,
they seem to be covered in "Notes on Linux as a guest".  However,
is this text accurate: 

  "Some old configurations may depend on deprecated
   high-numbered SCSI and IDE disks.  This does not work in
   recent versions of Linux."

The upstreamed Linux driver supports 15 SCSI major numbers.
Are 13 of these the "deprecated high-numbered" ones, or were
there more than 15 at some point?

--
Justin
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