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

[Geert Uytterhoeven]

On Fri, Dec 11, 2015 at 1:41 PM, Petr Mladek <pmladek@xxxxxxxx> wrote:
> On Fri 2015-12-11 12:10:02, Geert Uytterhoeven wrote:
>> On Wed, Dec 9, 2015 at 2:21 PM, Petr Mladek <pmladek@xxxxxxxx> 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.
>
> Ãh, 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@xxxxxxxxx>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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