Perhaps this is the gcc problem: GCC Bugzilla Bug 21828 [4.0 Regression] debug info omitted for uninitialized variables http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21828 Dave > Looking at the vmlinux files with dwarfdump and gdb 6.3 alone, I can > see now that in the target 2.6.16 xen kernel (built with gcc 4.0.0, > if that matters), what is happening is that for static kernel data that is > declared without being initialized, its data type information is being > completely left out of the debug info section. > > So, taking kernel/pid.c as an example, symbols such as "pid_hash", > "pidhash_shift" and "last_pid" are declared uninitialized. Looking > at the 2.6.16 xen kernel built with gcc 4.0.0: > > # gdb vmlinux > GNU gdb Red Hat Linux (6.3.0.0-1.63rh) > Copyright 2004 Free Software Foundation, Inc. > GDB is free software, covered by the GNU General Public License, and you are > welcome to change it and/or distribute copies of it under certain conditions. > Type "show copying" to see the conditions. > There is absolutely no warranty for GDB. Type "show warranty" for details. > This GDB was configured as "x86_64-redhat-linux-gnu"...Using host libthread_db library "/lib64/tls/libthread_db.so.1". > > (gdb) whatis last_pid > type = <data variable, no debug info> > (gdb) whatis pid_hash > type = <data variable, no debug info> > (gdb) whatis pidhash_shift > type = <data variable, no debug info> > (gdb) > > Then looking at a non-xen 2.6.16-era kernel built with gcc 4.1.0: > > # gdb /usr/dumps/kdump/vmlinux > GNU gdb Red Hat Linux (6.3.0.0-1.63rh) > Copyright 2004 Free Software Foundation, Inc. > GDB is free software, covered by the GNU General Public License, and you are > welcome to change it and/or distribute copies of it under certain conditions. > Type "show copying" to see the conditions. > There is absolutely no warranty for GDB. Type "show warranty" for details. > This GDB was configured as "x86_64-redhat-linux-gnu"...Using host libthread_db library "/lib64/tls/libthread_db.so.1". > > (gdb) whatis last_pid > type = int > (gdb) whatis pid_hash > type = struct hlist_head *[4] > (gdb) whatis pidhash_shift > type = int > (gdb) > > I don't believe the "xen" angle makes a difference. I only have > 2.6.17-era xen kernels as a reference -- built with gcc 4.1.1 -- and > they do not exhibit this behavior. > > I presume that this affects files other than kernel/pid.c, but haven't > checked any further. > > So it would be interesting to know whether an upgrade in compilers > would make a difference. > > Regardless of that, I'll still come up with a fix and release for this, > since there's really nothing I can do with kernels of this ilk except > to work around their shortcomings. If the debug data's not there, > it's not there... > > Thanks, > Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
