Re: [PATCH 2/3] Implement new features needed for handling SystemTap probes

[Tom Tromey <tromey@redhat.com>]

>>>>> "Mark" == Mark Kettenis <mark.kettenis@xs4all.nl> writes:

Tom> The static probes in this case are intended to be source- (but not
Tom> binary-) compatible with DTrace. 

Mark> Don't you mean the other way around?  As far as I can tell the
Mark> SystemTap macros have different names than their DTrace counterparts.
Mark> And I'd say that for GDB it's only binary compatibility that really
Mark> matters here.

No, the SystemTap-provided <sdt.h> has compatibility macros with the
same names as the DTrace macros.

It doesn't try to be binary-compatible.  I don't know how the DTrace
<sdt.h> works at all...

Mark> So you are saying that, at least in principle, it should be possible
Mark> to use the SystemTap toolchain on any ELF-based system to do
Mark> user-space tracing without needing any kernel support?  That'd be cool.

Nope, just the static markers coming from <sdt.h>.  The rest of
SystemTap is Linux-specific, dynamically creating and loading kernel
modules.

The probes still have some value outside of SystemTap.  With patch #3 in
this series, you can use them to better implement "next-over-throw", for
C++ debugging.  This is because GCC's unwinder has a probe in it that is
used by GDB.

Tom