[SeaBIOS] SEABIOS and DOS compatibility

Kevin O'Connor kevin at koconnor.net
Sun Nov 11 20:32:39 CET 2012

On Sun, Nov 11, 2012 at 06:44:53PM +0100, Gerhard Wiesinger wrote:
> Hello,
> I bisected down 2 DOS 6.22 compatibility issues:
> 1.) COMMAND.COM can not be loaded high,
> 9c98517c938d20c38f537d516c71b30bb60c3ea0 is the first bad commit
> Looks like and UMB generated which is not recognizeable ...
> Before: 9E80-9F7F: 4k EBDA, 9F80-9FFF: 2k UNUSED, really unused or
> used for option ROMs?
> After: 9F00-9FFF: 4k EBDA, now the 2k area is somewhere above and
> will be used by memory managers???

Thanks.  Can you post your qemu command line and the SeaBIOS output
(-chardev stdio,id=seabios -device
isa-debugcon,iobase=0x402,chardev=seabios) from both a working run and
the non-working run?  Also, can you provide the exact text reported by
msdos on success and failure.

> 2.) 59d6ca52a7eba5b1f4f2becf70fd446dccaf0a2e is the first bad commit
> Opening a file and closing a file raises a 386 exception

That's odd - nothing in this commit impacts the disk code.  Maybe a
slightly different memory layout is triggering some other bug.

I have an MSDOS 6.22 floppy image - but I don't see either of these
issues.  Can you provide the steps needed to reproduce them?


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