linux-kernel - Re: [PATCH] ARM: BUG() dies silently

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Date:	Tue, 5 Apr 2011 11:02:56 -0500
From:	"Ramirez Luna, Omar" <omar.ramirez@...com>
To:	Simon Glass <sjg@...omium.org>
Cc:	Stephen Boyd <sboyd@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	lk <linux-kernel@...r.kernel.org>,
	lak <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ARM: BUG() dies silently

Hi,

On Tue, Apr 5, 2011 at 12:46 AM, Simon Glass <sjg@...omium.org> wrote:
> On Mon, Apr 4, 2011 at 7:29 PM, Ramirez Luna, Omar <omar.ramirez@...com> wrote:
> ...
>> I am using CONFIG_BUG=y, however I don't have CONFIG_DEBUG_BUGVERBOSE
>> and hence I fall into the part which doesn't print the file and the
>> line where the BUG was found.
>>
>> With Simon's patch if my .config had:
>>
>> CONFIG_BUG=y
>> CONFIG_GENERIC_BUG is not set
>
> In this case the patch is like a nop.
>
>> CONFIG_DEBUG_BUGVERBOSE is not set
>>
>> I would fall into the same BUG definition that is causing issues:
>>
>> #define BUG()           do { *(int *)0 = 0; } while (1)
>>
>> OTOH, is not like "Use generic BUG() handler" gives the choice of
>> removing GENERIC_BUG given that it is not prompted in menuconfig and
>> auto selected, if this is the intention is there any reason to keep
>> the #else part of /* not CONFIG_GENERIC_BUG */? there is no way we can
>> use it with this patch, right?
>
> Well, er, the intention is that you use the patch. I kept the old code
> around since people can then simply change the Kconfig option and be
> back where they were, as indeed you have. I would be happy to remove
> the old behavior, but I was concerned about a possible roasting in
> this forum. Changing long-established behavior is sometimes tricky.

Yes, but you can't change the Kconfig because it is not prompted with
your patch, if that was the intention then an option to de/select
GENERIC_BUG or not is needed:

arch/arm/Kconfig
@@ -204,6 +204,10 @@ config MMU
          Select if you want MMU-based virtualised addressing space
          support by paged memory management. If unsure, say 'Y'.

+config GENERIC_BUG
+       bool "Generic BUG"
+       default y
+       depends on BUG

Regards,

Omar
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