Re: RFA: ia64 portion of libunwind patch

[Marcel Moolenaar <marcel@xcllnt.net>]

On Fri, Oct 31, 2003 at 02:25:14PM -0500, J. Johnston wrote:
> 
>   Andrew> I'm also wondering if the unwind code (probably impossible I
>   Andrew> know) could use a callback to request the memory rather than
>   Andrew> require an entire buffer.
> 
> The way the libunwind interface works nowadays, the only buffering
> that is strictly needed is for the unwind info of the procedure being
> looked up (which usually has a size of the order of tens of bytes).
> But this would require doing a binary search on the unwind-table in
> the target space, which might be rather slow (there is one 24-byte
> entry in this table per procedure).  Thus, it might be easier (and
> certainly faster) to buffer the unwind table inside gdb.

Getting the unwind tables for remote targets can take a while if the
load module is large and the communication is slow (say 9600 baud).
Since libunwind already does its own caching, we may be better off
not caching in gdb. This also works better with dynamic unwind
information, which cannot be cached without some way of validating
whether the cached information is still correct or not.

-- 
 Marcel Moolenaar	  USPA: A-39004		 marcel@xcllnt.net