diff options
author | Michal Januszewski <spock@gentoo.org> | 2007-10-16 01:28:26 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 09:43:13 -0700 |
commit | 8bdb3a2d7df48b861972c4bfb58490853a228f51 (patch) | |
tree | febc4fbe0fd90e4677fe7703350ce349ddbfc342 /Documentation/fb | |
parent | cc54f46e39dff9891dd334ef158a238ff5a9ffd2 (diff) | |
download | kernel_samsung_tuna-8bdb3a2d7df48b861972c4bfb58490853a228f51.zip kernel_samsung_tuna-8bdb3a2d7df48b861972c4bfb58490853a228f51.tar.gz kernel_samsung_tuna-8bdb3a2d7df48b861972c4bfb58490853a228f51.tar.bz2 |
uvesafb: the driver core
uvesafb is an enhanced version of vesafb. It uses a userspace helper (v86d)
to execute calls to the x86 Video BIOS functions. The driver is not limited
to any specific arch and whether it works on a given arch or not depends on
that arch being supported by the userspace daemon. It has been tested on
x86_32 and x86_64.
A single BIOS call is represented by an instance of the uvesafb_ktask
structure. This structure contains a buffer, a completion struct and a
uvesafb_task substructure, containing the values of the x86 registers, a flags
field and a field indicating the length of the buffer. Whenever a BIOS call
is made in the driver, uvesafb_exec() builds a message using the uvesafb_task
substructure and the contents of the buffer. This message is then assigned a
random ack number and sent to the userspace daemon using the connector
interface.
The message's sequence number is used as an index for the uvfb_tasks array,
which provides a mapping from the messages coming from userspace to the
in-kernel uvesafb_ktask structs.
The userspace daemon performs the requested operation and sends a reply in the
form of a uvesafb_task struct and, optionally, a buffer. The seq and ack
numbers in the reply should be exactly the same as those in the request.
Each message from userspace is processed by uvesafb_cn_callback() and after
passing a few sanity checks leads to the completion of a BIOS call request.
Signed-off-by: Michal Januszewski <spock@gentoo.org>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Paulo Marques <pmarques@grupopie.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/fb')
0 files changed, 0 insertions, 0 deletions