Re: [Xen-devel] [PATCH v2 1/2] xen: add config option to include failing condition in BUG_ON() message

[Jan Beulich <jbeulich@xxxxxxxx>]

On 14.01.2020 17:00, Jürgen Groß wrote:
> On 14.01.20 16:47, Jan Beulich wrote:
>> On 09.01.2020 14:48, Juergen Gross wrote:
>>> --- a/xen/Kconfig.debug
>>> +++ b/xen/Kconfig.debug
>>> @@ -81,6 +81,12 @@ config PERF_ARRAYS
>>>     ---help---
>>>       Enables software performance counter array histograms.
>>>   
>>> +config DEBUG_BUGVERBOSE
>>> +   bool "Verbose BUG_ON messages"
>>> +   default DEBUG
>>> +   ---help---
>>> +     In case a BUG_ON triggers additionally print the triggering
>>> +     condition on the console.
>>>   
>>>   config VERBOSE_DEBUG
>>
>> While I can see reasons to put this here, doing so means the option
>> will be unavailable in non-EXPERT release builds. Is it intended to
>> be that way?
> 
> I can move it either to xen/Kconfig or in Kconfig.debug out of the
> "if expert" section if you want.

I think this would be better, but give others a chance to voice
opinions.

>>> --- a/xen/include/xen/lib.h
>>> +++ b/xen/include/xen/lib.h
>>> @@ -8,7 +8,12 @@
>>>   #include <xen/string.h>
>>>   #include <asm/bug.h>
>>>   
>>> +#define BUG_ON_VERBOSE(p) do { if (unlikely(p)) BUG_VERBOSE(#p);  } while 
>>> (0)
>>> +#ifdef CONFIG_DEBUG_BUGVERBOSE
>>> +#define BUG_ON(p)  BUG_ON_VERBOSE(p)
>>
>> Looks like this will fail to build on Arm? Also - any particular
> 
> Uh, shame on me!
> 
>> reason for the introduction of the separate BUG_ON_VERBOSE(),
>> when BUG_ON() could directly use BUG_VERBOSE()? I don't think we
>> want to encourage use of BUG_ON_VERBOSE() elsewhere ...
> 
> I wanted to offer that option. If you want me to remove it I wouldn't
> mind.

As above - unless there are good reasons (making others to agree
with you to have it), I'd prefer to not see it being independently
usable, at least for the time being.

Jan

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