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

From: Petr Mladek <[email-masked]>
Date: Fri, 11 Dec 2015 13:41:59 +0100

On Fri 2015-12-11 12:10:02, Geert Uytterhoeven wrote:
> On Wed, Dec 9, 2015 at 2:21 PM, Petr Mladek <[email-masked]> 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

Thanks a lot for report,
Petr