Messages in this thread | | | Date | Sat, 12 May 2007 14:21:37 +0200 | From | Alexander van Heukelum <> | Subject | Re: x86 setup rewrite tree ready for flamage^W review |
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On Thu, May 10, 2007 at 03:48:08PM -0700, H. Peter Anvin wrote: > > It doesn't probe the hardware in dangerous ways. (Search for mode_scan > > in video.S) It works by trying to set a mode via the normal > > AH=0/AL=mode/int 0x10 method for all possible values of mode. It then > > checks if the bios reports the new mode as being set and reads a few > > standard vga registers to determine if it is a text mode. It's > > completely independent of the CONFIG_VIDEO_SVGA stuff. > > It's dangerous, all right (which is why it doesn't do it by default), > since you have no guarantee that the BIOS doesn't totally vomit on these > calls -- or, like my laptop, take about a minute before giving up > finding nothing.
I see. I think I just have too much trust in the biosses. Anyhow, the 'scan' option has always taken quite a bit of time, usually between 30 seconds and a minute.
> Anyway, I re-implemented scanning and pushed it out to the git tree; > please try it out as it does absolutely nothing on any of my machines.
I can confirm that it works for at least one computer over here (a six months old x86_64 machine with ATI ES1000-based on-board graphics). Some non-vesa modes including a nice 100x30 one with 8x16 font are found by the 'scan' option. No 100x60, however, but that is not a regression.
> > I thought the 32-bit jump was required to come before the segment loads. > > Does this code load values from the gdt, or are they just loaded as real > > mode segments? As long as it does not crash it does not matter, because > > head.S reloads them again. > > Once CR0.PE is set, segments are loaded from the GDT.
I believe you :).
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