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[Query] Re: dwarf unwinder (only works on i386/x86_64)
- From: Prerna Saxena <prerna at linux dot vnet dot ibm dot com>
- To: Mark Wielaard <mjw at redhat dot com>
- Cc: systemtap at sourceware dot org, roland at redhat dot com
- Date: Tue, 28 Apr 2009 23:34:54 +0530
- Subject: [Query] Re: dwarf unwinder (only works on i386/x86_64)
- References: <1239977157.2336.33.camel@fedora.wildebeest.org>
Hi Mark,
An elementary query regarding the dwarf-unwinder implementation...
Mark Wielaard wrote:
......
I am working on using the dwarf unwinder also for user space
backtracing. First using the debug_frame tables that we also are using
for the kernel case, but maybe switching to the eh_frame tables (it
isn't clear which one is really the most accurate at the moment, we
might need to consult both, but I am trying to avoid doing that for
now).
I was trying to contrast the ".eh_frame" vs ".debug_frame"
specifications for keeping track of stack backtraces. Both appear rather
similar wrt information they maintain.
The Exception header ".eh_frame" section seems to be present in vmlinux
even when kernel is compiled without debuginfo.
i. what gcc flags cause this section to be compiled ?
ii. This section seemingly appears to be a better bet than DWARF to base
the unwinder on--- because a ".debug_frame" based unwinder might not be
useful in case of a kernel complied without debuginfo.
Looks like I'm missing some reasoning here, could you throw some light ?
:-)
Cheers,
Mark
Regards,
--
Prerna Saxena
Linux Technology Centre,
IBM Systems and Technology Lab,
Bangalore, India