Markers in (non-module) kernel code?

From: Theodore Ts'o
Date: Fri Oct 03 2008 - 15:16:40 EST



I've been playing with adding some markers into ext4 to see if they
could be useful in solving some problems along with Systemtap. It
appears, though, that as of 2.6.27-rc8, markers defined in code which is
compiled directly into the kernel (i.e., not as modules) don't show up
in Module.markers:

kvm_trace_entryexit arch/x86/kvm/kvm-intel %u %p %u %u %u %u %u %u
kvm_trace_handler arch/x86/kvm/kvm-intel %u %p %u %u %u %u %u %u
kvm_trace_entryexit arch/x86/kvm/kvm-amd %u %p %u %u %u %u %u %u
kvm_trace_handler arch/x86/kvm/kvm-amd %u %p %u %u %u %u %u %u

(Note the lack of any of the kernel_sched_* markers, and the markers I
added for ext4_* and jbd2_* are missing as wel.)

Systemtap apparently depends on in-kernel trace_mark being recorded in
Module.markers, and apparently it's been claimed that it used to be
there. Is this a bug in systemtap, or in how Module.markers is getting
built? And is there a file that contains the equivalent information
for markers located in non-modules code?

Thanks, regards,

- Ted

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