At 06:48 PM 11/2/1999 +1100, Simon wrote:

<code fragment snipped>

>The "jump to myself" would be the "while (1); " at the end of the
>function.  Basically, when you call these prom routines, they shouldn't
>return!  Unfortunately you'll need to emulate some of these calls if you
>want to do a complete DECstation simulator.  The document referenced by
>Tohru may help you here.

Ahhhh.... when examining the assembly code for the kernel, we observed that
at one point it jumped to location bfc00088, which corresponds to a PROM
function.  Unfortunately, that location held "deadbeef," so the simulator
just kinda died, printing out "deadbeef" all over the screen.  We kinda
hacked around it by slightly modifying the simulator code so that when the
PC encountered any values of bfc0xxxx, it essentially skipped over the PROM
functions and resumed operation on the next instruction after the branch
delay slot after the first call to a PROM function.  This resulted in the
"jump to myself" situation.





Ji Bae@Cornell University
jhb8@cornell.edu
Computer Systems Lab -- http://www.csl.cornell.edu
http://www.people.cornell.edu/pages/jhb8