Messages in this thread |  | | Date | Fri, 09 Dec 2005 08:24:15 +0800 | From | "Antonino A. Daplas" <> | Subject | Re: [PATCH 1/1 2.6.15-rc4-git1] Fix switching to KD_TEXT |
| |
Knut Petersen wrote: > Every framebuffer driver relies on the assumption that the set_par() > function > of the driver is called before drawing functions and other functions > dependent > on the hardware state are executed. > > This assumption is false in two cases, and one is a genuine linux > bug: > > 1: Whenever you switch from X to a framebuffer console for the very > first time, there is a chance that a broken X system has _not_ set > the mode to KD_GRAPHICS, thus the vt and framebuffer code > executes a screen redraw and several other functions before a > set_par() is executed. This is believed to be not a bug of linux > but a bug of X/xdm. > > 2: Whenever a switch from X to a framebuffer console occures, > the pan_display() function of the driver is called once before > the set_par() function of the driver is called. Code path: > complete_change_console -> redraw_screen -> fbcon_switch -> > bit_update_start-> fb_pan_display -> xyz_pan_display. > This is clearly a bug of linux.
This part, #2, can be easily fixed.
> > Although our primary goal must be to fix linux bugs and not to work > around bugs of X, the patch fixes both of the cases. > > The advantage and correctness of this patch should be obvious. Yes, it > does add a possibly slow call to the fb_set_par() function, but at this > point it is necessary. > > Signed-off-by: Knut Petersen <Knut_Petersen@t-online.de>
Sorry, NAK for now. Unless other people agree that it is okay for them to have an unconditional call to set_par() for every console switch. Note that the set_par() in some drivers is terribly slow (several seconds at least).
Let's wait a few days, if nobody disagrees with you, so be it.
Tony - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |