kbuild: introduce new option to enhance section mismatch analysis

[~andy/linux] / lib / Kconfig.debug

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 14fb355e3caacc1311adfcaf52435e974c715dce..748e72be6e68364225846cadf5dd6d6a6990e9a8 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -79,6 +79,36 @@ config HEADERS_CHECK
          exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
          your build tree), to make sure they're suitable.
 
+config DEBUG_SECTION_MISMATCH
+       bool "Enable full Section mismatch analysis"
+       default n
+       help
+         The section mismatch analysis checks if there are illegal
+         references from one section to another section.
+         Linux will during link or during runtime drop some sections
+         and any use of code/data previously in these sections will
+         most likely result in an oops.
+         In the code functions and variables are annotated with
+         __init, __devinit etc. (see full list in include/linux/init.h)
+         which result in the code/data being placed in specific sections.
+         The section mismatch anaylsis are always done after a full
+         kernel build but enabling this options will in addition
+         do the following:
+         - Add the option -fno-inline-functions-called-once to gcc
+           When inlining a function annotated __init in a non-init
+           function we would loose the section information and thus
+           the analysis would not catch the illegal reference.
+           This options tell gcc to inline less but will also
+           result in a larger kernel.
+         - Run the section mismatch analysis for each module/built-in.o
+           When we run the section mismatch analysis on vmlinux.o we
+           looses valueable information about where the mismatch was
+           introduced.
+           Running the analysis for each module/built-in.o file
+           will tell where the mismatch happens much closer to the
+           source. The drawback is that we will report the same
+           mismatch at least twice.
+
 config DEBUG_KERNEL
        bool "Kernel debugging"
        help