cvs commit: src/sys/net if_vlan.c
marcel at xcllnt.net
Fri Aug 4 20:02:16 UTC 2006
On Fri, Aug 04, 2006 at 01:14:22PM -0400, John Baldwin wrote:
> > So, putting the kdb_backtrace() under KDB is not a matter of said
> > function not being present without KDB, it's that we don't want
> > to emit backtraces when debugging is not enabled. Backtraces are
> > a debugging tool and it makes sense to emit them only when the
> > kernel is configured for debugging.
> In practice this ends up being redundant though as to have kdb_backtrace()
> actually do anything you have to have DDB in your kernel config, which
> requires KDB.
That's really an implementation detail. What if we get a new debugger
backend that allows backtraces? What if the GDB backend is extended to
The point is that kdb_backtrace() is there if you want a backtrace and
you call it based on whatever option that makes sense at the call-site
or even unconditionally if that's the right thing.
Whether there's actually a backend that can make a backtrace is really
a seperate issue. We just happen to implement backtracing and unwinding
by debuggers, but with an unwinder in the kernel on ia64, we really
don't need a debugger in order to make a backtrace and it's not that
unrealistic that I create a backend that can only do backtraces...
> Places that call kdb_enter() aren't all #ifdef KDB IIRC. It's
> just a feature that kdb_foo() functions become NOPs when the kernel isn't
> configured for debugging, so I think the #ifdef KDB's would be redundant.
None of the kdb_*() functions in src/sys/kern/subr_kdb.c turn into
NOPs when option KDB is not present. They are all unconditionally
functional by design and should therefore be called conditionally
Marcel Moolenaar USPA: A-39004 marcel at xcllnt.net
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