Date: Tue, 08 Nov 2011 22:55:59 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Arnaud Lacombe <lacombar@gmail.com> Cc: Attilio Rao <attilio@FreeBSD.org>, freebsd-current@FreeBSD.org Subject: Re: Using Instruction Pointer address in debug interfaces [Was: Re: vm_page_t related KBI [Was: Re: panic at vm_page_wire with FreeBSD 9.0 Beta 3]] Message-ID: <4EB9975F.4090601@FreeBSD.org> In-Reply-To: <CAJ-FndDOWpotphH4pmn0S6QqJybx74A2Kt4a8aiT96x0f2cRZA@mail.gmail.com> References: <CACqU3MU_Bk%2BcObCiUa2XtM7fLkSpSDzOZqoZ=khNOR-_6ptYYQ@mail.gmail.com> <CAJ-FndDOWpotphH4pmn0S6QqJybx74A2Kt4a8aiT96x0f2cRZA@mail.gmail.com>
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[cc list trimmed] on 08/11/2011 22:34 Attilio Rao said the following: > 2011/11/8 Arnaud Lacombe <lacombar@gmail.com>: >> To avoid future complaints about the fact that I would be only "talk" >> without "action", I did implement what I suggested above. As it is >> quite a large patch-set, I will not post it directly here, however, it >> is available on github: > > I really think that this is way too dependent by the good health of > your tool, thus that is highly fragile. > > However, you may have more luck by just the core of your kernel > changes here, for comment and leave alone all the (ptr -> > LOCK_FILE/LOCK_LINE conversion). > > Said that, I think this logic is too fragile and likely won't be as > effective as __FILE__/__LINE__ in many cases. I agree. If we were able to somehow automatically, magically, easily and correctly determine an instruction pointer of a caller, then it would make sense to ditch explicit passing of __FILE__/__LINE__ arguments in favor of doing instruction pointer decoding. But if we are just replacing explicit passing of (well-known) macros __FILE__/__LINE__ with explicit passing of THIS_IP, then I don't see a point. Apologies if I missed the rationale for this change. -- Andriy Gapon
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