SuperH DTF connection protocol

Stephen Clarke
Mon Aug 20 18:16:00 GMT 2001

> Andrew Stubbs wrote:

> The standard setup for newlib on the sh (I don't know about other
> platforms) is to communicate with the outside world (read, write, open,
> ...) using a trap. As I understand it this is something understood by the
> gdb simulator - it does not work on an actual sh chip and board.

Is it true that these traps do not work on real target hardware?
It seems very unlikely!

> DTF is our protocol for communicating with programs running on real boards
> via a network connection through the built in debug link - when running
> linux we can use a network card or serial port, but that doesn't work
> with hello world.
> We want to add support for this to newlib. It just means changing (a copy
> of) the sys/sh/syscalls.c file and including a bunch of extra functions.

Why not install a trap handler to catch the traps and turn them
into the appropriate dtf calls?  (If you hadn't said otherwise above,
I would have guessed this is the technique used on real target hardware,
but perhaps with the trap handler in ROM.)

This could all be done in libgloss, rather than newlib, which I'm told
shouldn't be concerned with this stuff.

Stephen Clarke, Micro Cores & Development Tools, STMicroelectronics
Phone:1-408-922-4062, Fax:1-408-895-3069,
Mail:  STMicroelectronics, 1060 E. Brokaw Rd., San Jose, CA 95131.

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