Bug 496516

Summary:	enable double-buffering in the vmware fbdev driver
Product:	Gentoo Linux	Reporter:	Christopher Friedt <chrisfriedt>
Component:	[OLD] Core system	Assignee:	Gentoo Kernel Bug Wranglers and Kernel Maintainers <kernel>
Status:	RESOLVED NEEDINFO
Severity:	normal	Keywords:	PATCH
Priority:	Normal
Version:	10.1
Hardware:	All
OS:	Linux
URL:	https://plus.google.com/107058277812335526223/posts/2B9UA8Y3wD2
Whiteboard:
Package list:		Runtime testing required:	---
Attachments:	linux-3.10.7-gentoo-enable-vmwgfx-double-buffering.patch

Description Christopher Friedt 2013-12-30 17:11:07 UTC

The (non-kms) VMWare framebuffer driver (drivers/gpu/drm/vmwgfx/vmwgfx_fb.c) previously did nothing when confronted with the FBIOPAN_DISPLAY ioctl. The FBIOPAN_DISPLAY ioctl is used for multi-buffering and page-flipping in most display drivers.

VMWare's "virtual SVGA hardware" does not support VBE function 0x07 (Set/Get Display Start) which is commonly used for page-flipping, as outlined here:

http://web.fe.up.pt/~pfs/aulas/lcom2011/proj/topics.html

The attached change allows the driver to emulate page-flipping.

Reproducible: Always

Steps to Reproduce:
1. open /dev/fb0
2. set yres_virtual to 2*yres
3. paint to back-buffer
4. send ioctl FBIOPAN_DISPLAY to send the back-buffer to the front
Actual Results:  
no change

Expected Results:  
new frame displayed on front buffer

Comment 1 Christopher Friedt 2013-12-30 17:21:14 UTC

Created attachment 366580 [details, diff]
linux-3.10.7-gentoo-enable-vmwgfx-double-buffering.patch

Comment 2 Tom Wijsman (TomWij) (RETIRED) gentoo-dev

2014-04-02 15:55:31 UTC

Can you send this to upstream and reply with a link to it?

Comment 3 Mike Pagano gentoo-dev

2014-05-01 17:56:48 UTC

Please comment if you've sent this patch upstream with the link.
Thanks.

Comment 4 Christopher Friedt 2014-05-01 19:06:56 UTC

I need to talk to Thomas Hellstrom iirc, and possibly also Dave Airlie to see if this patch is OK as is, or if it needs further veneering.

Please keep the bug open for now - sorry for the delay.

Comment 5 Mike Pagano gentoo-dev

2014-10-07 11:32:24 UTC

It's been 5 months, any update on this?