On 2013-10-30 12:17, Borislav Petkov wrote: > On Mon, Oct 28, 2013 at 09:58:58AM +0100, Jan Kiszka wrote: >> CC: Rob Landley <rob@xxxxxxxxxxx> >> CC: linux-doc@xxxxxxxxxxxxxxx >> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >> --- >> Documentation/gdb-kernel-debugging.txt | 159 +++++++++++++++++++++++++++++++++ >> 1 file changed, 159 insertions(+) >> create mode 100644 Documentation/gdb-kernel-debugging.txt >> >> diff --git a/Documentation/gdb-kernel-debugging.txt b/Documentation/gdb-kernel-debugging.txt >> new file mode 100644 >> index 0000000..944f2d2 >> --- /dev/null >> +++ b/Documentation/gdb-kernel-debugging.txt >> @@ -0,0 +1,159 @@ >> +Debugging kernel and modules via gdb >> +==================================== >> + >> +The kernel debugger kgdb, hypervisors like QEMU or JTAG-based hardware >> +interfaces allow to debug the Linux kernel and its modules during runtime >> +using gdb. Gdb comes with a powerful scripting interface for python. The >> +kernel provides a collection of helper scripts that can simplify typical >> +kernel debugging steps. This is a short tutorial about how to enable and use >> +them. It focuses on QEMU/KVM virtual machines as target, but the examples can >> +be transferred to the other gdb stubs as well. >> + >> + >> +Requirements >> +------------ >> + >> + o gdb 7.2+ (recommended: 7.4+) with python support enabled (typically true >> + for distributions) >> + >> + >> +Setup >> +----- >> + >> + o Create a virtual Linux machine for QEMU/KVM (see www.linux-kvm.org and >> + www.qemu.org for more details). For cross-development, >> + http://landley.net/aboriginal/bin keeps a pool of machine images and >> + toolchains that can be helpful to start from. >> + >> + o Build the kernel with CONFIG_DEBUG_INFO and CONFIG_KALLSYMS enabled, but >> + leave CONFIG_DEBUG_INFO_REDUCED off. >> + >> + o Install that kernel on the guest. >> + >> + Alternatively, QEMU allows to boot the kernel directly using -kernel, >> + -append, -initrd command line switches. This is generally only useful if >> + you do not depend on modules. See QEMU documentation for more details on >> + this mode. >> + >> + o Enable the gdb stub of QEMU/KVM, either >> + - at VM startup time by appending "-s" to the QEMU command line >> + or >> + - during runtime by issuing "gdbserver" from the QEMU monitor >> + console >> + >> + o cd /path/to/linux-build >> + >> + o Start gdb: gdb vmlinux >> + >> + Note: Some distros may restrict auto-loading of gdb scripts to known safe >> + directories. In case gdb reports to refuse loading vmlinux-gdb.py, add >> + >> + add-add-auto-load-safe-path /path/to/linux-build > > Only one "add-" should be enough :) Thanks, fixed. Need to update this file anyway. > > Btw, gdb is nice enough to tell me: > > $ gdb vmlinux > Reading symbols from /w/kernel/linux-2.6/vmlinux...done. > warning: File "/w/kernel/linux-2.6/scripts/gdb/vmlinux-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load". > To enable execution of this file add > add-auto-load-safe-path /w/kernel/linux-2.6/scripts/gdb/vmlinux-gdb.py Is that sufficient to be able to import all the sub-scripts as well? > line to your configuration file "/home/boris/.gdbinit". > To completely disable this security protection add > set auto-load safe-path / > line to your configuration file "/home/boris/.gdbinit". > For more information about this security protection see the > "Auto-loading safe path" section in the GDB manual. E.g., run from the shell: > info "(gdb)Auto-loading safe path" > > Other than that, that's a very cool stuff and I'll make sure to be using > it the next time. > > Acked-by: Borislav Petkov <bp@xxxxxxx> > Thanks! Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
