From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ross Lagerwall <ross.lagerwall@citrix.com>
Subject: Re: [PATCH v3] x86/NMI: Allow processing unknown NMIs
 when watchdog is enabled
Date: Mon, 1 Sep 2014 14:27:44 +0100
Message-ID: <54047450.2080004@citrix.com>
References: <1409156728-4995-1-git-send-email-ross.lagerwall@citrix.com>
	<53FF379C.8070701@citrix.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; Format="flowed"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
In-Reply-To: <53FF379C.8070701@citrix.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Andrew Cooper <andrew.cooper3@citrix.com>, Xen-devel <xen-devel@lists.xen.org>
Cc: Keir Fraser <keir@xen.org>, Jan Beulich <jbeulich@suse.com>
List-Id: xen-devel@lists.xenproject.org

On 08/28/2014 03:07 PM, Andrew Cooper wrote:
>>   Run an NMI watchdog on each processor.  If a processor is stuck for
>> -longer than the **watchdog\_timeout**, a panic occurs.
>> +longer than the **watchdog\_timeout**, a panic occurs.  When `force` is
>> +specified, in addition to running an NMI watchdog on each processor,
>> +unknown NMIs will still be processed.
>>
>>   ### watchdog\_timeout
>>   > `= <integer>`
>> diff --git a/xen/arch/x86/nmi.c b/xen/arch/x86/nmi.c
>> index c4427a6..873427f 100644
>> --- a/xen/arch/x86/nmi.c
>> +++ b/xen/arch/x86/nmi.c
>> @@ -43,7 +43,18 @@ static DEFINE_PER_CPU(unsigned int, nmi_timer_ticks);
>>
>>   /* opt_watchdog: If true, run a watchdog NMI on each processor. */
>>   bool_t __initdata opt_watchdog = 0;
>> -boolean_param("watchdog", opt_watchdog);
>> +
>> +/* watchdog_force: If true, process unknown NMIs when running the watchdog. */
>> +bool_t watchdog_force = 0;
>> +
>> +static void __init parse_watchdog(char * s)
>> +{
>> +    opt_watchdog = !!parse_bool(s);
>
> A lot of code in Xen gets the use of parse_bool() wrong.  In this case,
> opt_watchdog will be set if garbage is passed in the parameter, which is
> a change in behaviour from before.
>

This is not a change in behavior from before. A bool param if specified 
on the command-line is set to true unless explicitly set to a false-like 
value (e.g. this is how a bare parameter like "watchdog" enables the 
watchdog).

As it has been committed, the behavior has been changed and means 
setting "watchdog" on the command-line does not result in the watchdog 
being enabled.

-- 
Ross Lagerwall