printk/nmi: increase the size of NMI buffer and make it configurable

[deliverable/linux.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index bccc1d607be540ebb44fe494446039ceffd6f577..a9c4aefd5436edf12d6bda5ab775fbee3e7a8fd8 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -862,6 +862,28 @@ 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_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
+         to avoid a deadlock. The value defines the size as a power of 2.
+
+         NMI messages are rare and limited. The largest one is when
+         a backtrace is printed. It usually fits into 4KB. Select
+         8KB if you want to be on the safe side.
+
+         Examples:
+                    17 => 128 KB for each CPU
+                    16 =>  64 KB for each CPU
+                    15 =>  32 KB for each CPU
+                    14 =>  16 KB for each CPU
+                    13 =>   8 KB for each CPU
+                    12 =>   4 KB for each CPU
+
 #
 # Architectures with an unreliable sched_clock() should select this:
 #