Messages in this thread | | | Date | Tue, 23 Jul 2013 11:36:28 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH, re-send] Always trap on BUG() |
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* H. Peter Anvin <hpa@zytor.com> wrote:
> On 07/15/2013 03:27 PM, Russell King - ARM Linux wrote: > > On Mon, Jul 15, 2013 at 03:16:12PM -0700, Andrew Morton wrote: > >> I've been thinking for a while that CONFIG_BUG=n is a pretty dumb thing > >> to do, and that maintaining it (and trying to fix the warnings it > >> produces) aren't worth the effort and that we should remove the whole > >> thing. Perhaps your patch changes that calculus, dunno. Please discuss. > > > > This isn't about introducing "CONFIG_BUG=n" - this is about making a > > kernel with CONFIG_BUG=n build without producing tonnes and tonnes of > > warnings, as it does today. It makes building randconfig pretty > > useless to find what could be more important warnings. > > > > Well, there are three alternatives here, right: > > 1. We can use unreachable(), which means that the compiler can assume it > never happens.
AFAICS this is dangerous as it loses warnings and moves execution into la-la-land without any obvious sign at the C level.
> 2. We can trap without metadata.
This is what the patch does.
> 3. We can trap with metadata (current CONFIG_BUG=y).
That is still kept with the patch.
> I am *guessing* this does 2, but it isn't clear.
Yes, that's what it does - and I think it's the best of all worlds:
Acked-by: Ingo Molnar <mingo@kernel.org>
(the crazies can keep a separate patch to remove even more of BUG() to win a K or two.)
Thanks,
Ingo
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