When switching from a color depth of 32 bits/pixel (bpp) to 8, 15, or 16 bpp either the drawing will be extremely slow such that the Screen Preferences dialog will take a couple seconds to redraw, or drawing will be fine at the lower color depth but when trying to switch back to 32 bpp the following error is displayed: "The screen mode could not be set: General system error".
The result depends upon the amount of video memory. If using a resolution of 1280x1024, and the video memory is >= 16 MB, the slow drawing occurs; however, if there is only 8 MB of video memory, drawing is fine but you can't switch back to 32 bpp color depth as described above. This second case might depend upon whether the video driver uses the virtual screen size to compute the required video memory. When switching back to 32 bpp, the virtual screen height in the display_mode struct passed to the video driver is double the actual screen height; thus, with a resolution of 1280x1024, the amount of memory required is 1280 x 2048 x 4 = 10 MB which is greater that 8 MB.
Actually, when switching back to 32 bpp, the virtual screen height is always double the actual screen height, but the error message does not occur if there is enough video memory to cover it.
These problems seemed to have initially appeared between r28289 and r28303. That is, these problems did not occur under r28289, but did occur under r28303.
Is it possible that the cause of this problem also caused the problem described by Bruno on Oct 27 in his message entitled "Weird Process Controller Behavior"?
Should I file a bug report on this problem? Regards, Gerald