From 1cdf25d704f7951d02a04064c97db547d6021872 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Mon, 28 Apr 2008 02:12:44 -0700 Subject: [PATCH] kbuild: create a way to create preprocessor constants from C expressions The use of enums create constants that are not available to the preprocessor when building the kernel (f.e. MAX_NR_ZONES). Arch code already has a way to export constants calculated to the preprocessor through the asm-offsets.c file. Generate something similar for the core kernel through kbuild. Signed-off-by: Sam Ravnborg Signed-off-by: Christoph Lameter Cc: Andy Whitcroft Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: Rik van Riel Cc: Mel Gorman Cc: Jeremy Fitzhardinge Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Kbuild | 56 ++++++++++++++++++++++++++++++++++++++++++++++++-------- kernel/bounds.c | 19 +++++++++++++++++++ 2 files changed, 67 insertions(+), 8 deletions(-) create mode 100644 kernel/bounds.c diff --git a/Kbuild b/Kbuild index 1570d24..7136de7 100644 --- a/Kbuild +++ b/Kbuild @@ -1,19 +1,54 @@ # # Kbuild for top-level directory of the kernel # This file takes care of the following: -# 1) Generate asm-offsets.h -# 2) Check for missing system calls +# 1) Generate bounds.h +# 2) Generate asm-offsets.h (may need bounds.h) +# 3) Check for missing system calls ##### -# 1) Generate asm-offsets.h +# 1) Generate bounds.h + +bounds-file := include/linux/bounds.h + +always := $(bounds-file) +targets := $(bounds-file) kernel/bounds.s + +quiet_cmd_bounds = GEN $@ +define cmd_bounds + (set -e; \ + echo "#ifndef __LINUX_BOUNDS_H__"; \ + echo "#define __LINUX_BOUNDS_H__"; \ + echo "/*"; \ + echo " * DO NOT MODIFY."; \ + echo " *"; \ + echo " * This file was generated by Kbuild"; \ + echo " *"; \ + echo " */"; \ + echo ""; \ + sed -ne $(sed-y) $<; \ + echo ""; \ + echo "#endif" ) > $@ +endef + +# We use internal kbuild rules to avoid the "is up to date" message from make +kernel/bounds.s: kernel/bounds.c FORCE + $(Q)mkdir -p $(dir $@) + $(call if_changed_dep,cc_s_c) + +$(obj)/$(bounds-file): kernel/bounds.s Kbuild + $(Q)mkdir -p $(dir $@) + $(call cmd,bounds) + +##### +# 2) Generate asm-offsets.h # offsets-file := include/asm-$(SRCARCH)/asm-offsets.h -always := $(offsets-file) -targets := $(offsets-file) +always += $(offsets-file) +targets += $(offsets-file) targets += arch/$(SRCARCH)/kernel/asm-offsets.s -clean-files := $(addprefix $(objtree)/,$(targets)) + # Default sed regexp - multiline due to syntax constraints define sed-y @@ -40,7 +75,8 @@ define cmd_offsets endef # We use internal kbuild rules to avoid the "is up to date" message from make -arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c FORCE +arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \ + $(obj)/$(bounds-file) FORCE $(Q)mkdir -p $(dir $@) $(call if_changed_dep,cc_s_c) @@ -49,7 +85,7 @@ $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild $(call cmd,offsets) ##### -# 2) Check for missing system calls +# 3) Check for missing system calls # quiet_cmd_syscalls = CALL $< @@ -58,3 +94,7 @@ quiet_cmd_syscalls = CALL $< PHONY += missing-syscalls missing-syscalls: scripts/checksyscalls.sh FORCE $(call cmd,syscalls) + +# Delete all targets during make clean +clean-files := $(addprefix $(objtree)/,$(targets)) + diff --git a/kernel/bounds.c b/kernel/bounds.c new file mode 100644 index 0000000..85bb281 --- /dev/null +++ b/kernel/bounds.c @@ -0,0 +1,19 @@ +/* + * Generate definitions needed by the preprocessor. + * This code generates raw asm output which is post-processed + * to extract and format the required data. + */ + +#define __GENERATING_BOUNDS_H +/* Include headers that define the enum constants of interest */ + +#define DEFINE(sym, val) \ + asm volatile("\n->" #sym " %0 " #val : : "i" (val)) + +#define BLANK() asm volatile("\n->" : : ) + +void foo(void) +{ + /* The enum constants to put into include/linux/bounds.h */ + /* End of constants */ +} -- 2.7.4