Date: Fri, 4 Aug 2006 13:14:22 -0400 From: John Baldwin <jhb@freebsd.org> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: Yar Tikhiy <yar@comp.chem.msu.su>, src-committers@freebsd.org, cvs-all@freebsd.org, cvs-src@freebsd.org, Sam Leffler <sam@errno.com> Subject: Re: cvs commit: src/sys/net if_vlan.c Message-ID: <200608041314.24161.jhb@freebsd.org> In-Reply-To: <6B15CBE0-00E0-4F64-A652-4A4B614975C2@xcllnt.net> References: <200608030959.k739x9N6007207@repoman.freebsd.org> <20060804070348.GR97316@comp.chem.msu.su> <6B15CBE0-00E0-4F64-A652-4A4B614975C2@xcllnt.net>
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On Friday 04 August 2006 12:23, Marcel Moolenaar wrote: > On Aug 4, 2006, at 12:03 AM, Yar Tikhiy wrote: > > > Just noticed that many calls to kdb_backtrace() are under "#ifdef > > KDB" while subr_kdb.c is marked as standard in /sys/conf/files and > > the function itself is always available (yet can do nothing.) > > > > Should calls to kdb_backtrace() be put under "#ifdef KDB"? If they > > should, it can justify introducing the combined printf+trace function. > > subr_kdb.c is indeed unconditional. The reason is that it contains > the interface functions and you should not make interface functions > optional if modules can reference them. > > The KDB option is there to tell that one wants debugging features > enabled. This means for example that serial drivers react to the > line break condition by going into the debugger. Without the KDB > option line break conditions just result in a 0-character in the > input stream. > > 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. 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. -- John Baldwin
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