Eric W. Biederman wrote:
No. It allows full access to all IO ports. Otherwise it would have never been able to get to the system timer.
I was afraid of that.
So not only will it have to emulate x86 instructions it will have to emulate some of the generic x86 hardware setup.
Exactly. But in this case emulation is more predictable than making certain your hardware is setup in a legacy conforming mode.
Hey, I'm totaly in agreement with you. No convincing necessary. *grin*
It probally dosen't have to go all the way emulating a legacy PC enviroment but it looks like a few things will have to be dealt with. Restricting IO to legacy VGA registers and the allocated card IO locations is a good idea. That should flush out any other issues of this sort. There probally aren't that many though.
In other news I recompiled my VBIOS with the delay routine just doing a 'ret' rathen then all that crazy timer stuff and testbios now completes on my target rather than going into the infinite loop it did before.
Still don't get a signon message but it does do pretty much the same thing that ADLO+vbios does. H & V sync with the timeings correct for text mode but only a black screen. So thats some progress. Interesting to note that running the no-delay vbios on my desktop PCI works the same as with the delays.