From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <386CD9C2.D00DDE27@mvista.com> Date: Fri, 31 Dec 1999 10:28:50 -0600 From: Jim Lewis MIME-Version: 1.0 To: Brendan.Simon@ctam.com.au CC: linux-embedded , Cross-GCC , linuxppc-embedded Subject: Re: cross-compiling & debugging embedded-linux apps References: <386C3615.E14AE6DD@ctam.com.au> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Brendan J Simon wrote: > I have a powerpc embedded system (MPC860, 4MB Flash, 16MB RAM, ethernet, > rs232). I have compiled the kernel and can boot it using a root > filesystem via initrd or nfs. The root filesystem is a minimal one that > was on the linuxppc-embedded ftp site. It basically has /bin/sh, > /bin/ls and a few libraries in /lib. > > I NEED to be able to compile apps from the sources. I have managed to > cross-compile ncurses and bash. I can't get bash to run at all (even a > statically compiled version). I get segmentaion faults. I'm currently > using SASH which I have cross-compiled as a static binary. I compiled a > test app (bjs1.c) which outputs a string every second. It is compiled > as a static binary (bjs1-static) and a shared binary (bjs1-shared). The > static binary works but the shared one does not. I assume it is some > library problem but I can't figure out what. I think you are right. What libraries are you linking against? I think the the minroot FS from the embedded FTP site uses libc 1.99. I have had nothing but trouble when trying to mix libraries. If you did build against different libraries, one way you could do is to create a new directory for your shared application and the shared objects you linked against. Make sure to include the ld.so.1 executable. Then, at the target SASH prompt, issue the following: > /test/ld.so.1 --library-path /test /test/bjs1-shared > The output of the sash > session is below. > > Stand-alone shell (version 1.0) > > ./bjs1-static > BJS1: Brendan was here > BJS1: Brendan was here > BJS1: Brendan was here > pid 7: killed (signal 2) > > > > ./bjs1-shared > pid 8: killed (signal 11) > > > > I have all the libraries on the root filesystem. The rpc.nfsd daemon > seems to read the entire file but sash says the process is killed with > signal 11 (segmentation fault). I have no idea how to debug this. I > don't think there is a simulator for the mpc860 as part of gdb. Is > there a way of debugging this on the target with powerpc-gdb and an > ethernet or serial connection ? Yes, there is. Dan posted some gdbserver sources a while back. That allows you to do cross debug. But you are likely to have the same problems building gdbserver that you are having with your simple test application. > > > How does the kernel know where to look for libraries ? I assume there > are some default locations like /lib. I haven't got an ld.so.conf setup > nor do I have ldconfig. The 'default' location seems to be built in to the executable. Usually, /lib/ld.so.1 is invoked and it tries to open ld.so.cache to determine where libraries are. If it cannot find /etc/ld.so.cache, then it just uses default locations that were "compiled in". The ld.so.cache is created by ldconfig, which reads ld.so.conf to determine how to build ld.so.cache. > > > It can't be that hard to get a simple 10 line program to execute as a > shared binary. It must be something really simple that I am missing. > > Thanks for any help, > Brendan Simon. -- Jim Lewis Sr. Field Applications Engineer MontaVista Software, Inc. (817)261-9088 http://www.mvista.com ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/