[SeaBIOS] Boot failure with MS-Dos 6.22 (due to bad BIOS build?)

Kevin O'Connor kevin at koconnor.net
Wed Feb 29 09:45:13 CET 2012

On Mon, Feb 27, 2012 at 04:25:09PM +0100, Jan Kiszka wrote:
> On 2012-02-27 10:51, Daniel P. Berrange wrote:
> > I'm seeing current QEMU GIT fail to boot MS-Dos 6.22 with the following
> > crash:
> > 
> > # qemu-system-x86_64 -fda ~/MS-DOS\ 6.22.img  -m 1 -curses

Does the error persist when run with "-m 2"?  If more memory fixes the
issue, then it is likely already fixed in upstream (commit 890d9851).
The bugs fixed in that commit are null pointer derefernce errors - in
SeaBIOS, a write to "NULL" actually alters the memory at address 0,
which can corrupt the interrupt table - these can lead to
unpredictable errors, as the timing between when an irq fires and when
the corruption occurs can vary.  DOS might overwrite the irq entries
with its own settings, and thus depending on timing may cover up the
error.  In short, I wouldn't assume the problem is the toolchain.


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