On Tue, 24 Sep 2002, Stas Sergeev wrote: > This problem exists only on some (modern?) cards for VESA > modes, but for VGA modes there must be no such problem at > all (Bart, do you really have any examples when this is a > problem even for VGA? Correct me then, please).
Well VGA only uses standard ports so the only problem is to pass the VBIOS initialization in the first place, that is executing the code at c000:0003 (or c800:0003, whereever the VBIOS is). On some graphics cards this init routine requires additional open ports and maybe even accessible MMIO. Some people reported black screens, or even machines hanging which happens when the VBIOS init routine is called. I'm not sure why this VBIOS init routine is always called if you set $_graphics, but at least it gets the video card into a clean state. This is esp. important if you use fbdev graphical textmodes on the console instead of the standard VGA textmode (80x25). Maybe by just bypassing the VBIOS init you can avoid this problem; I just have never looked into that possibility. The VBE 2.0 spec defines a protected mode interface - if DOSEMU would use that it could ask which ports should be used and opened. However it does not currently use that interface, I don't know how to do that and am not able to test it anyway (being far away from my desktop where I could take some risks). Bart - To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
