invalid argument error when setting yres_virtual in fb_var_screeninfo

Question

I\'m trying to make an application for linux that writes directly to the framebuffer /dev/fb0. In order to make it double buffered I try to make the virtual screen be double

Answer 1

To save anyone a headache in the future, there is a way to properly double buffer using low level graphics on linux (such as /dev/fb0). However per this thread: https://forum.odroid.com/viewtopic.php?f=55&t=8741 it is not possible to truly double buffer the framebuffer by creating a virtual framebuffer of double the size of the original one (I've read that the raspberry PI might be an exception to this rule because it is backed by a different driver).

The right way to double buffer using low level graphics on linux is to go through libdrm (or /dev/dri/card0). There is a really nice example that I followed myself here: https://github.com/dvdhrm/docs/blob/master/drm-howto/modeset-vsync.c. It wasn't very hard to convert my /dev/fb0 code to /dev/dri/card0 code.

Anyways I hope I've helped someone out here who might come across this in the future.

Answer 2

This is a common question and it is caused by the limitation of the video driver. E.g., Intel's 810 chipset only allows 640x480 resolution and the Broadcom's limit the width to no more than 1200 (http://www.raspberrypi.org/phpBB3/viewtopic.php?f=66&t=29968).

Not much you can do here, unless you change the driver or the videocard itself (if possible).

EDIT: if you are on a PC, try using the vesafb, not the intel's driver.

There's a hint here: http://www.mail-archive.com/debian-russian@lists.debian.org/msg27725.html