linux-kernel - Re: [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable

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Date:	Fri, 11 Dec 2015 13:50:16 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Petr Mladek <pmladek@...e.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Daniel Thompson <daniel.thompson@...aro.org>,
	Jiri Kosina <jkosina@...e.com>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"adi-buildroot-devel@...ts.sourceforge.net" 
	<adi-buildroot-devel@...ts.sourceforge.net>,
	Cris <linux-cris-kernel@...s.com>,
	Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	linux-s390 <linux-s390@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	sparclinux <sparclinux@...r.kernel.org>
Subject: Re: [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and
 make it configurable

On Fri, Dec 11, 2015 at 1:41 PM, Petr Mladek <pmladek@...e.com> wrote:
> On Fri 2015-12-11 12:10:02, Geert Uytterhoeven wrote:
>> On Wed, Dec 9, 2015 at 2:21 PM, Petr Mladek <pmladek@...e.com> wrote:
>> > --- a/init/Kconfig
>> > +++ b/init/Kconfig
>> > @@ -866,6 +866,28 @@ config LOG_CPU_MAX_BUF_SHIFT
>> >                      13 =>   8 KB for each CPU
>> >                      12 =>   4 KB for each CPU
>> >
>> > +config NMI_LOG_BUF_SHIFT
>> > +       int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
>> > +       range 10 21
>> > +       default 13
>> > +       depends on PRINTK && HAVE_NMI
>>
>> Symbol NMI_LOG_BUF_SHIFT does not exist if its dependencies are not met.
>
> Åh, the NMI buffer is enabled on arm via NEED_PRINTK_NMI.
>
> The buffer is compiled when CONFIG_PRINTK_NMI is defined. I am going
> to fix it the following way:
>
>
> diff --git a/init/Kconfig b/init/Kconfig
> index efcff25a112d..61cfd96a3c96 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -870,7 +870,7 @@ config NMI_LOG_BUF_SHIFT
>         int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
>         range 10 21
>         default 13
> -       depends on PRINTK && HAVE_NMI
> +       depends on PRINTK_NMI
>         help
>           Select the size of a per-CPU buffer where NMI messages are temporary
>           stored. They are copied to the main log buffer in a safe context

Makes sense, as kernel/printk/nmi.c is compiled if PRINTK_NMI is set.

Acked-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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