SystemTap provides an instrumentation infrastructure for systems running the Linux 2.6 kernel. It allows users to write scripts that probe and trace system events for monitoring and profiling purposes. SystemTap's framework allows users to investigate and monitor a wide variety of wide variety of kernel functions, system calls, and other evens that occur in both kernel-space and user-space.
The following are the Known Issues that apply to the systemtap package in Red Hat Enterprise Linux 5.4
Running some user-space probe test cases provided by the
systemtap-testsuite package fail with an
Unknown symbol in module error on some architectures. These test cases include (but are not limited to):
Because of a known bug in the latest SystemTap update, new SystemTap installations do not unload old versions of the
uprobes.ko module. Some updated user-space probe tests provided by the systemtap-testsuite package use symbols available only in the latest
uprobes.ko module (also provided by the latest SystemTap update). As such, running these user-space probe tests result in the error mentioned earlier.
If you encounter this error, simply run
to manually remove the older
module before running the user-space probe test again.(BZ#499677)
SystemTap currently uses GCC to probe user-space events. GCC is, however, unable to provide debuggers with precise location list information for parameters. In some cases, GCC also fails to provide visibility on some parameters. As a consequence, SystemTap scripts that probe user-space may return inaccurate readings. (BZ#239065