Michael Devore <[EMAIL PROTECTED]> writes: > Great. Now that HIMEM is getting wider distribution to the eager > hundreds or thousands, I've additionally collected problem reports > with buggy BIOS support for BIOS method and a failing A20 always on > method. It's like a dam busted somewhere upstream.
I do not envy you. It sounds like you cannot trust the BIOS status code, so you need to test whether it really enabled/disabled the gate. Or, just tell the user their BIOS is buggy and to get a new machine. :-) What do you mean by "failing A20 always on method"? Do you mean that A20 is always on but it is not detected as such? (Would that imply that the test_a20 procedure is broken?) > I am considering dropping the the KBC method since KBC-2 seems to > replace it without problems on all reported machines. This is not too surprising. The Linux kernel initialization code enables A20. Granted that it only has to enable A20 and it only runs once, but it is known to work on millions of machines... In HIMEM64 parlance, the Linux code tries "always on", BIOS, KBC-2, and "fast", in that order. There are some slight differences. Linux tests the actual state of A20 for every method. In KBC-2, Linux has a longer (or at least different) delay where you have "pulse output port". In the test_a20 code, Linux has delays (outb ...) all over the place, possibly to deal with instruction reordering issues (see http://www.mail-archive.com/[EMAIL PROTECTED]/msg00023.html), or possibly not. In general, the Linux code is almost identical to what HIMEM64 does now, except that it does not even try the "KBC" method, and it tries KBC-2 before "fast". For the record, your latest HIMEM64 and EMM386 work great on all of my test systems. Thank you for all the hard work! - Pat ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ Freedos-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/freedos-devel
