Re: embedded system emulator help

["Frank Ch. Eigler" <fche at redhat dot com>]

Hi -


On Mon, Mar 07, 2005 at 09:06:31AM -0800, Imran Shafiq wrote:

> [...]  automotive subsystems are comprised of [ECU] Electronic
> Control Units (e.g fujitsu mb90f598, Powerpc mpc 566) connected
> through a BUS system usually CAN.  [...]  So does that means I have
> to implement the whole instruction set for every ECU??

That's right.  If you want to simulate software compiled for a given
platform, and a model of that platform is not already available, then
there is some coding to do.  I believe there is no PowerPC model in
sid at the moment.


> I also have to simulate UART, Timer etc

Some UART and timer models are already included in sid.  They may be
useful as is, or may serve as a basis for derivation.


> It should be possible to check the data on the bus So that would
> mean I have to implement the CAN protocol??

Well, one doesn't simulate a "protocol" per se, rather entities that
perform it.  You would need to pick a level of abstraction at which
the simulator should model a CAN system.  This could be at the
controller level, wire level, perhaps even some software level. This
allows you to trade of hardware fidelity versus modeling simplicity.


> Simulator should also report stack overflows or memory
> limitations.

Some of this is often best done by instrumentation added by the
compiler (check gcc's -fstack-limit options).  Or a simulator could
also model "missing" physical memory that would trigger bus errors
upon attempted access.  Think of the latter as mprotect(PROT_NONE).


> IS all this possible with SID considering the fact that i have to do
> it in 5 months :) .

Probably, if you pick another CPU architecture that is already
well-supported in sid, such as ARM.  If nearly all of your software 
is to be written in C, you could argue that the difference in the
processors is almost immaterial.


> Where can i start with an example. any pointers?

I would start with one of the classic sid configurations: running an
application linked with the eCos RTOS on a model of a board such as
the ARM PID.  Analyze the application, eCos linkages, memory and
peripheral layout, and the corresponding sid configuration.


- FChE

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