Re: Newbie gdb / gdbserver question with x86-64 and -m32 g++ goodness

[Michael Snyder <msnyder@vmware.com>]

Jerry 85032 wrote:
> So I am new to using gdb and gdbserver.  And I'm trying to use it on a pretty
> complex program.  But that's okay, I can't get it to run on a simple system,
> so let's talk about that.
> 
> I created the usual c++ Hello World.  I have access to two identical Centos
> 5 development systems connected with tcp.
> 
> #include <iostream>
> int main(int argc, char *argv[])
> {
>     std::cout << "Hello World." << std::endl;
>     return -1;
> 
> }
> 
> 
> If I compile my hello world with:
> 
> $ g++ -g hello.cpp -o hello
> 
> Then everything works pretty much as expected.  I can run it on either
> system.  I can use gdb on one system, connect to gdbserver on the other
> system, and everything seems to work fine.  I set a break at main on my
> local system, gdbserver the program on the target, use gdb to tell it to
> run, and Hello World prints out on the gdbserver system.
> 
> But if I compile it with -m32, and repeat the process, then the two systems
> seem to be fighting over architecture issues.  I receive messages like
> register badly formatted.  Or "warning: Selected architecture i386 is not
> compatible with reported target architecture i386:x86-64".  This seems to
> happen regardless of how I tell gdb to set the architecture, either i386 or
> i386:x86-64.

I believe you need to give the "set architecture" command
before the "target remote" command.  This should work...


> 
> g++ -g -m32 hello.cpp -o hello
> 
> So I gather much of my problem is because I'm ignorant.  And I don't really
> understand what -m32 does, although I know our hideously complex system IS
> compiled that way.
> 
> Apart from that, I am using:
> 
> $ g++ --version
> g++ (GCC) 4.1.2 20080704 (Red Hat 4.1.2-46)
> 
> $ gdbserver --version
> GNU gdbserver Fedora (6.8-37.el5)
> This gdbserver was configured as "x86_64-redhat-linux-gnu"
> 
> $ cat /etc/redhat-release 
> CentOS release 5.4 (Final)
> 
> Can someone help clue me in?
> 
> Thank you