BTX loader problem on specific hardware

Guido Falsi mad at
Sat Jun 18 08:10:48 UTC 2011

On 06/17/11 18:01, John Baldwin wrote:

>> I'm not sure, but maybe rdmsr or wrmsr are generating exceptions which
>> are not managed by BTX? I could be wrong, I really dont' know that much
>> about the internals of CPUs.
> Well, the old BTX didn't allow full access to CR registers.  Running in
> real mode, there should be no problems with any MSR accesses though in
> the new BTX.

I thought that, but I could not identify any other big diffs from the 
other BIOS I had a look at.

>> I obviously have the disassembled code available, but not posting it
>> here because I'm not sure what policies there are about disassembled
>> code on the lists.
> You can post a URL perhaps (or just send it to me directly if you wish).

I put there a disassembled.txt with the relevant parts disassembled and 
put in some kind of order(you'll anyway need to jump a round a little, 
could not make it any better). There's a small comment identifying the 
critical area.

I put there a dump of the full BIOS and the IDT, just in case.

Thank you again!

Guido Falsi <mad at>

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