Re: [Xen-devel] [PATCH 2 of 5] blkif.h: Provide more complete documentation of the blkif interface

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

On Feb 7, 2012, at 10:51 AM, Ian Jackson wrote:

> Justin T. Gibbs writes ("[Xen-devel] [PATCH 2 of 5] blkif.h: Provide more 
> complete documentation of the blkif interface"):
>>  o Document the XenBus nodes used in this protocol
> 
> Awesome.  But I don't think all of these are really supposed to be
> part of the guest interface, so you should probably mention which ones
> are.
> 
> For example,
> 
>> + * params
>> + *      Values:         string
> 
> this is not intended for use by guests and they should not look at it.

Guests can export back-end devices.  Here at Spectra we do this all the
time. :-)

It would be hard to implement a blkback driver without this information.
The comment at the top of your email implies you're okay with it being
in this file, but that I should mark "local-end use only" nodes?

> 
>> + * virtual-device
>> + *      Values:         <uint16_t> (XEN_*_MAJOR << 8 | Minor)
> 
> This should be a reference to docs/misc/vbd-interface.txt.  But isn't
> this also encoded in the device path in xenstore ?

It would appear so.  Should this path naming convention be mandated by
this file?  Since "virtual-device" exists, it seems that front-ends should
read it, not parse the path, to determine this information.

--
Justin
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