[PATCH 1/3] Make it possible for the linker to discard local symbolsfrom vmlinux

[David Howells]

Make it possible for the linker to discard local symbols from vmlinux as they
cause vmlinux to balloon when CONFIG_KALLSYMS=y and they cause dump_stack() and
get_wchan() to produce useless information under some circumstances.

With this we add a config option (CONFIG_STRIP_ASM_SYMS) that will cause the
build to supply -X to the linker to tell it to strip temporary local symbols.

This doesn't seem to cause gdb any problems.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 Makefile     |    4 ++++
 init/Kconfig |    8 ++++++++
 2 files changed, 12 insertions(+), 0 deletions(-)


diff --git a/Makefile b/Makefile
index 22d7584..359470f 100644
--- a/Makefile
+++ b/Makefile
@@ -589,6 +589,10 @@ LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
 LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
 LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)
 
+ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
+LDFLAGS_vmlinux	+= -X
+endif
+
 # Default kernel image to build when no specific target is given.
 # KBUILD_IMAGE may be overruled on the command line or
 # set in the environment
diff --git a/init/Kconfig b/init/Kconfig
index f068071..50c267a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -737,6 +737,14 @@ config KALLSYMS_EXTRA_PASS
 	   you wait for kallsyms to be fixed.
 
 
+config STRIP_ASM_SYMS
+	bool "Strip assembler-generated symbols during link"
+	default n
+	help
+	  Strip internal assembler-generated symbols during a link (symbols
+	  that look like '.Lxxx') so they don't pollute the output of
+	  get_wchan() and suchlike.
+
 config HOTPLUG
 	bool "Support for hot-pluggable devices" if EMBEDDED
 	default y

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