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                          Building and Using
                      GDB Tracepoints for Linux

The tracepoint support has two components: a loadable kernel module,
and patches to GDB.


Prerequisites

The kernel module requires Linux 2.6.19.1, or newer.  The GDB patches
are relative to the CVS sources as of sometime around Feb 21, 2007.
It seems that the Feb 27 weekly GDB snapshot works:

ftp://sourceware.org/pub/gdb/snapshots/current/gdb-weekly-6.6.50.20070227.tar.bz2


Kernel Module

To build the kernel module, type 'make' in the source directory (which
also contains this INSTALL file).  This should build you a file
'gtp.ko', which you can load with 'insmod gtp.ko' (as root).

I semi-recommend installing Linus's 'sparse' checker and building with
'make C=1'; this does some pickier typechecking on your code, and even
brings some kernel-specific knowledge into play, like checking that
pointers to userspace objects are used properly.  It's "semi-
recommended" because it didn't actually catch any problems for me, but
you never know; I'll take a static failure over a crash any day.

More experienced kernel hackers have told me Xen makes things much
more pleasant --- you don't have to crash the guest that's running
your development tools.  I haven't tried it yet because I didn't have
time, but it's probably smart.  I hate rebooting.


GDB Patches

The file 'gdb.patch' contains a patch for GDB that adds the
'linux-trace' target.  To apply it, cd to the top level of the source
tree, and use patch -p5.  Then build GDB in the usual way.  GDB is
happy to be run straight out of its build tree, if you don't want to
install it.

I'll work on getting these patches into the public GDB sources, but
it's not kludge-free, so it may not go quickly.