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This is the ABI for the two halves of a para-virtualized display driver. This protocol aims to provide a unified protocol which fits more sophisticated use-cases than a framebuffer device can handle. At the moment basic functionality is supported with the intention to extend: o multiple dynamically allocated/destroyed framebuffers o buffers of arbitrary sizes o better configuration options including multiple display support Note: existing fbif can be used together with displif running at the same time, e.g. on Linux one provides framebuffer and another DRM/KMS Future extensions to the existing protocol may include: o allow display/connector cloning o allow allocating objects other than display buffers o add planes/overlays support o support scaling o support rotation Note, that this protocol doesn't use ring macros for bi-directional exchange (PV calls/9pfs) bacause: o it statically defines the use of a single page for the ring buffer o it uses direct memory access to ring's contents w/o memory copying o re-uses the same idea that kbdif/fbif use which for this use-case seems to be appropriate ================================================== Rationale for introducing this protocol instead of using the existing fbif: ================================================== 1. In/out event sizes o fbif - 40 octets o displif - 40 octets This is only the initial version of the displif protocol which means that there could be requests which will not fit (WRT introducing some GPU related functionality later on). In that case we cannot alter fbif sizes as we need to be backward compatible an will be forced to handle those apart of fbif. 2. Shared page Displif doesn't use anything like struct xenfb_page, but DEFINE_RING_TYPES(xen_displif, struct xendispl_req, struct xendispl_resp) which is a better and more common way. Output events use a shared page which only has in_cons and in_prod and all the rest is used for incoming events. Here struct xenfb_page could probably be used as is despite the fact that it only has a half of a page for incoming events which is only 50 events. (consider something like 60Hz display) 3. Amount of changes. fbif only provides XENFB_TYPE_UPDATE and XENFB_TYPE_RESIZE events, so it looks like it is easier to get fb support into displif than vice versa. displif at the moment has 6 requests and 1 event, multiple connector support, etc. Signed-off-by: Oleksandr Grytsov <oleksandr_grytsov@epam.com> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Acked-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com> |
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.. | ||
hvm | ||
io | ||
callback.h | ||
elfnote.h | ||
event_channel.h | ||
features.h | ||
grant_table.h | ||
memory.h | ||
nmi.h | ||
physdev.h | ||
platform.h | ||
sched.h | ||
vcpu.h | ||
version.h | ||
xen-mca.h | ||
xen.h | ||
xenpmu.h |