Re: [Xen-devel] [PATCH RFC 2/5] blkif: document new blkback path xenstore node

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

El 01/06/15 a les 15.24, Wei Liu ha escrit:
> On Fri, May 22, 2015 at 11:18:55AM +0200, Roger Pau Monne wrote:
>> FreeBSD blkback uses the path xenstore node in order to fetch the path to
>> the underlying backing storage (either a block device or raw image). This
>> node is set by the hotplug scripts.
>>
>> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
>> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
>> Cc: Jan Beulich <jbeulich@xxxxxxxx>
>> Cc: Tim Deegan <tim@xxxxxxx>
>> ---
>>  xen/include/public/io/blkif.h | 12 ++++++++++--
>>  1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h
>> index 6baf7fb..b1e2245 100644
>> --- a/xen/include/public/io/blkif.h
>> +++ b/xen/include/public/io/blkif.h
>> @@ -89,8 +89,15 @@
>>   *      Values:         string
>>   *
>>   *      A free formatted string providing sufficient information for the
>> - *      backend driver to open the backing device.  (e.g. the path to the
>> - *      file or block device representing the backing store.)
>> + *      hotplug script to attach the device and provide a suitable
>> + *      handler (ie: a block device) for blkback to use.
>> + *
>> + * path
>> + *      Values:         string
>> + *      Notes: 11
>> + *
>> + *      A free formatted string that contains the path to the backing device
>> + *      for this blkback instance.
> 
> Why can't FreeBSD use the same "physical-device" node as Linux and
> NetBSD do? AIUI from reading this doc "physical-device" node already
> covers both "file" and "block device", i.e. it's a superset of the
> proposed "path" node here.

Not sure why, but "physical-device" is not documented at all in blkif.h.

I don't mind using the "physical-device" node, it's just that both Linux
and NetBSD use it to store the block device major and minor numbers, and
FreeBSD instead needs to store an absolute path (to either a block or
regular file). If people think it's fine to have different formats for
"physical-device" depending on the underlying OS I don't mind using it
on FreeBSD also.

Roger.


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel