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Re: "Cannot access memory at address 0x175f80"
I was specifying add-symbol-file, because when I start "orange",
none of the symbols from "apple" are accessible. In DDD, the source
code for Apple's files don't even appear in the "open source" menu. The
only 2 ways to make those files appear are 1) to run the program once,
then set breakpoints, then re-run, or 2) use the add-symbol-file
command. I admit I wasn't using it in an informed manner, but it worked
for the other symbols.
I tried a little experiment: I started gdb, used the
add-symbol-file command, then entered "break nc_signal_raised". It said
"Cannot access memory at address 0x175f9c". I then exited gdb, started
over, and this time, instead of add-symbol-file, ran the program. when
the program exitted, I typed "break nc_signal_raised", It said
"Breakpoint 1 at 0x40fb2f9f: file /sopt/ldv-dev/tools/src/main.cc, line
8.". So that was part of the problem.
Now the bad news. If I try to re-run, this particular breakpoint
can't be inserted. After that encouraging message above, I hit the
"run" button in ddd, and got:
(gdb) run snap1
(no debugging symbols found)...Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
ncsim: 05.00-s005: (c) Copyright 1995-2003 Cadence Design Systems, Inc.
ncsim: *W,DLNOHV: Unable to find an 'hdl.var' file to load in.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Error in re-setting breakpoint 1:
Function "nc_signal_raised" not defined.
Any Ideas?
Daniel Jacobowitz wrote:
On Fri, Sep 26, 2003 at 01:40:16PM -0400, Andrew Greenlaw wrote:
Hi. I'm debugging a C++ tool (called apple) that's loaded as a
dynamic library into a C - or C++ program (called orange) . Apple is
compiled with g++ 3.3.1, binutils 2.14, and debugging symbols are
enabled. Orange is a big unknown (meaning: I don't know how it was
compiled) and it has no debugging symbols. The gdb version is 5.3
Here are the flags used to compile Apple:
# -gdwarf-2 -g3 used to enable stepping through macro execution under
gdb 5.3 The explanation's under gdb 5.3 release notes.
Compile:g++ -std=c++98 -Wall -DLINUX -gdwarf-2 -g3 -D__USE_GNU
-D_GNU_SOURCE -fPIC file_name.cpp
Link:
g++ -shared $(LIBS) $(OBJSCHEF) $(PLIOBJSVCS_PLI)
InterfaceObjectVCS_PLI.o -o $@ -lc gdwarf-2 -g3 -fPIC
g++ -MD -std=c++98 -shared -lc -gdwarf-2 -g3 -fPIC <object files> -o
libapple.so
When I go to debug apple, I run "gdb <program name>", then use the
"add-symbol-file <apple's path & filename> -readnow" gdb comman to load
the symbols from apple. From there, I can set breakpoints in C++ class
methods, no problem. But, there is 1 function (so, non-OO code), where
if I try to set a breakpoint, I get the following:
(gdb) break nc_signal_raised
Cannot access memory at address 0x175f80
If I do an "nm" on the library, I get:
00175f80 T nc_signal_raised
Indicating that the address read by gdb is correct.
Unlikely, since the library is not loaded at a base address of 0.
On a related, but less important note, when use ddd to debug & go to
a source file, I always get: "<src_file_name>" is at address 0x10f5f0
<part_of_src_file_name> but contains no code.
And yet I can set breakpoints or step through the code. What's
going on?
Any help you can offer will be appreciated. I've been working on
this for 2 weeks, read every posting or piece of documentation I can
find. I'm at my wits' end!
Why are you using add-symbol-file? Is the loader not done as a dlopen,
i.e. are you dealing with something that has its own dynamic loader?
If it's dlopen'd, gdb should automatically handle it.
It seems unlikely that add-symbol-file without specifying a text offset
is right, too.
--
Andrew Greenlaw, Advanced Verification Group
Agere Systems of Ottawa, ON. Intranet page: http://ottawa/~andrewg/
E-mail: andrewg@agere.com, Phone: (613)768-8738, Fax: (768)768-8710
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"A mathematician is a device for turning coffee into theorems."
- Paul Erdos
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