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Re: [Embedded-pv-devel] [Xen-devel] [PATCH v13] This is the ABI for the two halves of a para-virtualized sound driver to communicate with each to other.
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Oleksandr Andrushchenko <andr2000@xxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>
- From: Julien Grall <julien.grall@xxxxxxx>
- Date: Mon, 28 Nov 2016 17:12:29 +0000
- Cc: lars.kurth@xxxxxxxxxx, iurii.konovalenko@xxxxxxxxxxxxxxx, vlad.babchuk@xxxxxxxxx, tim@xxxxxxx, dario.faggioli@xxxxxxxxxx, ian.jackson@xxxxxxxxxxxxx, andrii.anisov@xxxxxxxxx, olekstysh@xxxxxxxxx, embedded-pv-devel@xxxxxxxxxxxxxxxxxxxx, al1img@xxxxxxxxx, david.vrabel@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, oleksandr.dmytryshyn@xxxxxxxxxxxxxxx, joculator@xxxxxxxxx
- Delivery-date: Mon, 28 Nov 2016 17:12:37 +0000
- List-id: <embedded-pv-devel.lists.xenproject.org>
On 28/11/16 17:11, Andrew Cooper wrote:
On 28/11/16 16:59, Julien Grall wrote:
Hi,
On 28/11/16 15:43, Oleksandr Andrushchenko wrote:
On 11/28/2016 05:00 PM, Julien Grall wrote:
Hi Oleksandr,
On 28/11/16 14:56, Oleksandr Andrushchenko wrote:
On 11/28/2016 04:24 PM, Julien Grall wrote:
Hi Oleksandr,
On 28/11/16 14:12, Oleksandr Andrushchenko wrote:
On 11/28/2016 03:27 PM, Jan Beulich wrote:
+ *
+ * gref_dir_next_page - grant_ref_t, reference to the next page
describing
+ * page directory. Must be 0 if no more pages in the list.
If I am not mistaken 0 is a valid grant.
Then I will remove this sentence, anyways BE knows how many grefs
there
are for the buffer size given
BTW, xen-blkfrint.c:
#define GRANT_INVALID_REF 0
this is from where I got "Must be 0 if no more pages in the list."
GRANT_INVALID_REF is internally to Linux and never exposed in the PV
driver. So for me it is implementation details because ref 0 could be
allocated (log dump by Xen):
(XEN) -------- active -------- -------- shared --------
(XEN) [ref] localdom mfn pin localdom gmfn flags
(XEN) grant-table for remote domain: 2 (v1)
(XEN) [ 0] 0 0x99bf35 0x00000001 0 0x039000 0x19
(XEN) [ 1] 0 0x99bf33 0x00000001 0 0x039001 0x19
Grant reference 0 is reserved in the ABI for the paravirtual console.
Oh, so considering grant ref 0 as invalid in a PV protocol would be fine?
Cheers,
--
Julien Grall
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