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Date:      Fri, 24 Aug 2001 10:30:18 +0930
From:      Greg Lehey <grog@FreeBSD.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/conf options src/sys/i386/conf NOTES src
Message-ID:  <20010824103018.C21776@wantadilla.lemis.com>
In-Reply-To: <XFMail.010823175628.jhb@FreeBSD.org>; from jhb@FreeBSD.org on Thu, Aug 23, 2001 at 05:56:28PM -0700
References:  <20010824102127.A21776@wantadilla.lemis.com> <XFMail.010823175628.jhb@FreeBSD.org>

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On Thursday, 23 August 2001 at 17:56:28 -0700, John Baldwin wrote:
>
> On 24-Aug-01 Greg Lehey wrote:
>> On Thursday, 23 August 2001 at 17:27:10 -0700, John Baldwin wrote:
>>>
>>> On 24-Aug-01 Greg Lehey wrote:
>>>> On Thursday, 23 August 2001 at 13:32:21 -0700, John Baldwin wrote:
>>>>> jhb         2001/08/23 13:32:21 PDT
>>>>>
>>>>>   Modified files:
>>>>>     sys/conf             options
>>>>>     sys/i386/conf        NOTES
>>>>>     sys/kern             kern_shutdown.c
>>>>>     sys/sys              param.h
>>>>>   Log:
>>>>>   Add a new kernel option RESTARTABLE_PANICS.  If this option is present,
>>>>>   then one can restart from a panic by resetting the panicstr variable to
>>>>>   NULL.  This commit conditionalizes the previously committed
>>>>>   functionality
>>>>>   on this variable.  It also removes the __dead2 attribute from the
>>>>>   panic()
>>>>>   function so that when one continues from a panic() the behavior will
>>>>>   be predictable.
>>>>
>>>> The only way I can see to restart from a panic is to enter the
>>>> debugger and then return, and your code seems to bear this out.  Am I
>>>> missing something?  I would think that we can always return from the
>>>> debugger if we want to continue, and that the RESTARTABLE_PANICS and
>>>> check for null format string are not necessary.  Are you concerned
>>>> about people who will return from the debugger when they don't mean
>>>> to?  There are plenty of other ways to shoot down the system from the
>>>> debugger.
>>>
>>> Err. If you continue from the debugger, the panic() function calls boot()
>>> which
>>> reboots the system.  If you chagne panicstr to NULL, then we don't call
>>> boot()
>>> but return from panic(), thus effectively turning the panic() into a
>>> Debugger().
>>
>> So reset the panic string.
>
> Ah, no.  The intent is not to restart from all panics.  This lets
> you, the developer, decide at panic time if one wants to try and
> restart or not.  If you do, you clear panicstr, otherwise it panics
> normally.

Do you return from the debugger to panic?  I never do.

Greg
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