Porting advice or documentation request

["Svein E. Seldal" <Svein dot Seldal at solidas dot com>]

Hi all,

I'm working on this new gdb port, and more than often I'm stuck. I have 
been told that the d10v port is the most authorative template for how 
new targets should be written. Unfortunately it is impossible to learn 
anything about the d10v's hardware architecture on the net, so I find it 
a bit difficult to template from.

It is simple enough to copy the functions and such from the d10v's 
implemenation, but in many cases I have *no* idea what the function I'm 
implementing really does. E.g. what parts of the port are spesialised 
d10v parts and should not be copied, and which are general port 
implementations that should be copied, etc.

One pratical example is the struct frame_unwind table included in the 
target. It refers to "xxx_frame_this_id" and "xxx_frame_prev_register", 
which in turn performs some magic that I'm unable to make out. I 
understand from the docs that the xxx_frame_this_id should return the 
calling function's frame, but in the d10v port, there is much code that 
I dont understand what is.

And the list of gdbarch funtions are long, and my general impression is 
that I dont know which functions are required and which are there for 
special cases. What functions *must* I have implemented?

So please, please, please, does anyone have any pointers on how to 
understand gdb to get this port up and running? How can I best 
understand the gdbarch functions? I've read the gdb, gdb-internals 
manual and I'm grepping a lot of code, debugging gdb itself, but I'm 
still confused and uninformed. :(

So far I have at least a little bit. I have this TCP remote GDB server 
which talks to real hardware. And I've managed to get communication with 
it from GDB. I am able to place breakpoints, step code, etc.  But as 
soon as I do anything more complex, like dumping the frame or printing 
the registers it either dies with a segfault or issues a gdb error. But 
again, generally I dont really know *why* things fail, because I dont 
understand *what* I need to do or *where* to put it.

... help please.


Regards,
Svein