Re: Xcode preference gives me hope
Re: Xcode preference gives me hope
- Subject: Re: Xcode preference gives me hope
- From: Jim Ingham <email@hidden>
- Date: Tue, 14 Mar 2006 14:38:11 -0800
I was going to change to subject to "Jim takes the hope away"... but
I thought I'd let the body do that :-(
"Load CFM symbol information" does very little, and whatever it does
do is already done in the command-line gdb unless you've specifically
turned it off.
If "load CFM symbol information" is turned off, then gdb will arrange
not to be notified of CFM fragment loads, and will not search the CFM
fragment list to see what fragments are loaded. The only time gdb
will read a CFM fragment is if it happens to show up in a backtrace.
It is equivalent to setting "inferior-auto-load-cfm" to "off" in the
gdb command line.
gdb does scan the trace-back tables in CFM fragments (when it reads
them at all). So if there's traceback information in your CFM code,
we will be able to reconstruct functions from there. But this isn't
true symbol information. Reading this is slow however, since it
amounts to scanning all your program text for consecutive null's...
gdb does in fact have a buggy, slow and completely unmaintained xSYM
parser. So there is some chance that if you put your xSYM file in
the same directory as the fragment, and pass the path to the fragment
when it's loaded so we can find it, we might read some symbol
information out of the xSYM file. It worked - though poorly - 4
years ago; but that's the last time I tried it.
We don't do anything to actively break the CFM support but OTOH,
beyond what's needed for CodeWarrior (which due to the way it works
is very little) we don't plan on putting any effort into supporting
CFM. This was true before the Intel transition, and given that
there's no support for CFM in the Intel Mac OS X, it is even more
true now.
Sorry...
Jim
On Mar 14, 2006, at 1:48 PM, Mark Sanvitale wrote:
The Debugging pane of Xcode's preferences window includes the
checkbox "Load CFM symbol information". Now, I am no CFM expert,
but the "Carbon Porting Guide" discusses the limitations of using
GDB to debug a CFM app:
" you cannot set breakpoints at CFM functions, including those in
your application"
" GDB cannot use the symbol names in a CFM application"
which seems to contradict what I expect to happen from the
mentioned Xcode preference.
So, what specifically (i.e. at the gdb level) does this preference
do? Because if it does what I hope it does (i.e. remove above
limitations) then I want to do it in my command-line GDB sessions
for CFM apps.
Mark Sanvitale
Electrical Geodesics, Inc.
email@hidden
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