Re: MIPS simulator initializes LSI pmon vector table with code

[cgd@broadcom.com]

At Thu, 18 Apr 2002 19:47:04 +0000 (UTC), "Alexandre Oliva" wrote:
> There's a chunk of memory in LSI pmon that is supposed to contain
> pointers to `system call' handlers.

What Andrew said, and...

Actually, your patch seems incorrect.

The code at 0xbfc00200, etc., _ARE_ supposed to be code; in MIPS
they're various exception entry points.  If they are data which is
invalid code, the wrong thing will almost certainly happen.

I cannot believe that any monitor does what you describe (puts a table
of addresses here), as doing so (instead of putting vectors there)
would be fundamentally incompatible with the MIPS architecture.


> However, sim_open() will
> clobber the valid addresses it stores in this table with code bare
> code (as opposed to pointers to code) that was meant to catch invalid
> accesses.  This is obviously wrong.  I'm checking this in, since Frank
> Ch. Eigler and Eric Christopher agreed it was a reasonable thing to
> do.  I'll leave the complete fix for someone who has a real
> understanding of what was supposed to be done there.

Please justify this further, preferably with a pointer to
code that is broken by the old behaviour or to documentation.

Otherwise, I think this should almost certainly be backed out...



cgd