linux-kernel - Re: [PATCH] kexec: quiet down kexec reboot

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Message-ID: <20190425094115.GN3584@localhost.localdomain>
Date:   Thu, 25 Apr 2019 17:41:15 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Pavel Tatashin <pasha.tatashin@...een.com>
Cc:     sashal@...nel.org, kexec@...ts.infradead.org, jmorris@...ei.org,
        linux-kernel@...r.kernel.org, ebiederm@...ssion.com,
        dyoung@...hat.com
Subject: Re: [PATCH] kexec: quiet down kexec reboot

On 04/25/19 at 05:32pm, Baoquan He wrote:
> On 04/23/19 at 04:41pm, Pavel Tatashin wrote:
> > Here is a regular kexec command sequence and output:
> > =====
> > $ kexec --reuse-cmdline -i --load Image
> > $ kexec -e
> > [  161.342002] kexec_core: Starting new kernel
> > 
> > Welcome to Buildroot
> > buildroot login:
> > =====
> > 
> > Even when "quiet" kernel parameter is specified, "kexec_core: Starting
> > new kernel" is printed.
> 
> I personally don't like this change very much. 
> 
> kernel-parameters.txt tells that quiet disables most log messages, but
> not to disable log messages.
> 
> 	quiet           [KNL] Disable most log messages 
> 
> And kexec doesn't print many messages. When 'kexec -e' is executed,
> much critical work need be done in 1st kernel, and also in 2nd kernel
> till printed messages are seen. Sometime it could hang there without a
> notice, because we need shutdown all devices before it. Keeping it can
> at least tell which stage it is?
> 
> No strong objection, just we may need enable it manually if silent
> hang is met. Anyone has different opinion? 

Please ignore this mail, I must be dizzy. pr_notice looks good to me.

> > 
> > This message has  KERN_EMERG level, but there is no emergency, it is
> > a normal kexec operation, so quiet it down to appropriate KERN_NOTICE.
> > 
> > Machines that have slow console baud rate benefit from less output.
> > 
> > Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
> > ---
> >  kernel/kexec_core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> > index d7140447be75..fe13e86984ec 100644
> > --- a/kernel/kexec_core.c
> > +++ b/kernel/kexec_core.c
> > @@ -1171,7 +1171,7 @@ int kernel_kexec(void)
> >  		 * CPU hotplug again; so re-enable it here.
> >  		 */
> >  		cpu_hotplug_enable();
> > -		pr_emerg("Starting new kernel\n");
> > +		pr_notice("Starting new kernel\n");
> >  		machine_shutdown();
> >  	}
> >  
> > -- 
> > 2.21.0
> > 
> > 
> > _______________________________________________
> > kexec mailing list
> > kexec@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kexec
> 
> _______________________________________________
> kexec mailing list
> kexec@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec

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