RFA: ia64 portion of libunwind patch

[Andrew Cagney]

> Nothing which involves a syscall is acceptable in a tdep file.  That's
> what the t means - target support.

("tdep" mysteriously means "architecture vector support".  That "t" 
really no longer makes sense :-()

Yes, architecture vector shouldn't be directly making syscalls.  Instead 
the architecture specific code should use the target vector to obtain 
this system information.  Here I think the best option is to add another 
TARGET_OBJECT_xxxx variant and then use the target_read() method to pull 
in the data.

As for the native target side, ia64-linux-nat should export something 
like ia64_linux_child_read_partial that performs the syscall.  The 
tricky [er messy] part is wiring it into child_ops, I see there are lots 
of choices :-(

- define a nm-*.c macro and have that enable the assignment (ex #define 
NATIVE_TO_READ_PARTIAL ia64_linux_child?) (ref KILL_INFERIOR)

- have a callback set the to_read_partial method in child_ops 
(exec_set_find_memory_regions)

- modify all the targets so that each implements the new method

- others?

Is this information available via /proc?  In a core file?

Andrew

PS: Note this pending patch.  Dependant on the timing you or I may need 
to tweak the name.
http://sources.redhat.com/ml/gdb-patches/2003-10/msg00795.html