Re: [Xen-devel] [PATCH v4 2/2] xen/block: add multi-page ring support

[Julien Grall <julien.grall@citrix.com>]

On 20/05/15 15:56, Roger Pau Monné wrote:
> El 20/05/15 a les 15.21, Julien Grall ha escrit:
>> Hi,
>>
>> On 20/05/15 14:10, Bob Liu wrote:
>>> ---
>>>  drivers/block/xen-blkback/blkback.c |  12 ++++
>>>  drivers/block/xen-blkback/common.h  |   3 +-
>>>  drivers/block/xen-blkback/xenbus.c  |  85 +++++++++++++++++++++-------
>>>  drivers/block/xen-blkfront.c        | 110 ++++++++++++++++++++++++++----------
>>>  4 files changed, 161 insertions(+), 49 deletions(-)
>>>
>>> diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
>>> index 713fc9f..057890f 100644
>>> --- a/drivers/block/xen-blkback/blkback.c
>>> +++ b/drivers/block/xen-blkback/blkback.c
>>> @@ -84,6 +84,12 @@ MODULE_PARM_DESC(max_persistent_grants,
>>>                   "Maximum number of grants to map persistently");
>>>  
>>>  /*
>>> + * Maximum number of pages to be used as the ring between front and backend
>>> + */
>>> +unsigned int xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER;
>>
>> We will soon support 64KB page granularity with ARM64, although the PV
>> protocol will keep a 4KB page granularity.
>>
>> Can you clarify with granularity is used here? The one of the host or
>> the one of the PV protocol?
> 
> It's using 4K pages, because those are then granted to the domain
> handling the backend.

It would be nice to add a word in the comment.

Regards,

-- 
Julien Grall