Bug 496516 – enable double-buffering in the vmware fbdev driver

• Status: RESOLVED NEEDINFO
• Product: Gentoo Linux

[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) 2014-04-02 15:55:31 UTC]

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

[Comment 3 Mike Pagano 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 2014-10-07 11:32:24 UTC]

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