Simulator newbie question

I'm looking at ISS options for SW bringup of a fairly
elaborate SOC. The
CPU will be a 9x6E_S so it looks like the ARMulator supports
the
instruction set. Our toolchain is gnu. 
 
I want to have a decent understanding of the architecture of
the
simulator before I start adding our stuff. I've done some
cursory
browsing of the source. Is there any design documentation
for the GDB
simulators in general and the ARMulator in particular?
 
Assuming that there is little documentation to be discovered
 I'll
ask
a few questions for the hell of it:
 
The GDB remote protocol is RSP - it's well documented and I
assume this
is what the ARMul speaks over the socket it opens?
 
Why are there references to RDP and RDI buried in the ARMul?

 
Why is the "Angel" debug thingy from ARM in there?
Is it present by
default? I need a clean CPU.
 
It looks like armvirt.c is my attachment point for I/O
though I'll
probably have to get a hook into the instruction cycle
somewhere to
drive even a crude approximation of a timer.
 
All in all it looks like a decent place to start.
 
 
Time is a great teacher, but unfortunately it kills all its
pupils.~
Hector Berlioz

On Fri, Oct 26, 2007 at 01:54:13PM -0700, Mike Motyka
wrote:
> The GDB remote protocol is RSP - it's well documented
and I assume this
> is what the ARMul speaks over the socket it opens?

No, the simulators in sim/ get linked directly into GDB. 
Other, more
modern simulators run standalone and talk over a socket. 
Qemu for
instance.

I don't think you will find anyone else out here that knows
about
the ARMulator, though.  It hasn't seen active development in
a really
long while.

> Why are there references to RDP and RDI buried in the
ARMul? 

I think that ARM uses those to control their own
simulators.

-- 
Daniel Jacobowitz
CodeSourcery