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Re: [Xen-devel] [For Linux 4/4] xen/displif: add ABI for para-virtual display
- To: Stefano Stabellini <sstabellini@xxxxxxxxxx>
- From: Oleksandr Andrushchenko <andr2000@xxxxxxxxx>
- Date: Fri, 7 Apr 2017 20:51:42 +0300
- Cc: lars.kurth@xxxxxxxxxx, vlad.babchuk@xxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>, al1img@xxxxxxxxx, andrii.anisov@xxxxxxxxx, olekstysh@xxxxxxxxx, Julien Grall <julien.grall@xxxxxxx>, Oleksandr Grytsov <oleksandr_grytsov@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, joculator@xxxxxxxxx
- Delivery-date: Fri, 07 Apr 2017 17:51:51 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On 04/07/2017 08:50 PM, Stefano Stabellini wrote:
On Fri, 7 Apr 2017, Oleksandr Andrushchenko wrote:
On 04/07/2017 07:36 PM, Stefano Stabellini wrote:
On Fri, 7 Apr 2017, Oleksandr Andrushchenko wrote:
Hi, Julien!
On 04/07/2017 04:50 PM, Julien Grall wrote:
Hi Oleksandr,
On 07/04/17 09:30, Oleksandr Andrushchenko wrote:
+/*
+
******************************************************************************
+ * Back to front events delivery
+
******************************************************************************
+ * In order to deliver asynchronous events from back to front a
shared
page is
+ * allocated by front and its granted reference propagated to back
via
+ * XenStore entries (evt-ring-ref/evt-event-channel).
+ * This page has a common header used by both front and back to
synchronize
+ * access and control event's ring buffer, while back being a
producer of
the
+ * events and front being a consumer. The rest of the page after the
header
+ * is used for event packets.
+ *
+ * Upon reception of an event(s) front may confirm its reception
+ * for either each event, group of events or none.
+ */
+
+struct xendispl_event_page {
+ uint32_t in_cons;
+ uint32_t in_prod;
+ uint8_t reserved[56];
+};
+
+#define XENDISPL_EVENT_PAGE_SIZE 4096
This will be always the size of a grant (e.g xen page size), right? If
so, I
would prefer if you use XEN_PAGE_SIZE to so we can easily update Linux
in
the case Xen is using a different page size.
Note that the Front-end, Backend and Xen may use different page size, so
your drivers would need to cope with that. The current approach is to
always
use the page granularity of Xen.
Will the following satisfy the requirement?
#define XENDISPL_EVENT_PAGE_SIZE XEN_PAGE_SIZE
It is already defined in include/xen/page.h
Thank you, Stefano, but I meant if the change below
will fit the requirement, e.g. what Julien means is:
-#define XENDISPL_EVENT_PAGE_SIZE 4096
+#define XENDISPL_EVENT_PAGE_SIZE XEN_PAGE_SIZE
Julien, does this change work for you?
Sure, I think that would be OK. Also using XEN_PAGE_SIZE directly would
be OK.
Great, thanks
+#define XENDISPL_IN_RING_OFFS (sizeof(struct xendispl_event_page))
+#define XENDISPL_IN_RING_SIZE (XENDISPL_EVENT_PAGE_SIZE -
XENDISPL_IN_RING_OFFS)
+#define XENDISPL_IN_RING_LEN (XENDISPL_IN_RING_SIZE / sizeof(struct
xendispl_evt))
+#define XENDISPL_IN_RING(page) \
+ ((struct xendispl_evt *)((char *)(page) + XENDISPL_IN_RING_OFFS))
+#define XENDISPL_IN_RING_REF(page, idx) \
+ (XENDISPL_IN_RING((page))[(idx) % XENDISPL_IN_RING_LEN])
+
+#endif /* __XEN_PUBLIC_IO_DISPLIF_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
Cheers,
Thank you,
Oleksandr
Thank you,
Oleksandr
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