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From: Christoph Lameter <clameter@sgi.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Sam Ravnborg <sam@ravnborg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: apw@shadowen.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Subject: [rfc 07/10] Kbuild: Create a way to create preprocessor constants from C expressions
Date: Mon, 03 Mar 2008 16:04:59 -0800	[thread overview]
Message-ID: <20080304000733.688496611@sgi.com> (raw)
In-Reply-To: <20080304000452.514878384@sgi.com>

[-- Attachment #1: kbuild_cpp_export --]
[-- Type: text/plain, Size: 3194 bytes --]

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.

Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 Kbuild                 |   31 +++++++++++++++++++++++++++++--
 include/linux/bounds.h |   10 ++++++++++
 kernel/bounds.c        |   16 ++++++++++++++++
 3 files changed, 55 insertions(+), 2 deletions(-)

Index: linux-2.6/Kbuild
===================================================================
--- linux-2.6.orig/Kbuild	2008-02-29 19:27:40.000000000 -0800
+++ linux-2.6/Kbuild	2008-02-29 19:29:38.000000000 -0800
@@ -9,9 +9,10 @@
 #
 
 offsets-file := include/asm-$(SRCARCH)/asm-offsets.h
+bounds := include/linux/bounds.h
 
-always  := $(offsets-file)
-targets := $(offsets-file)
+always  := $(offsets-file) $(bounds)
+targets := $(offsets-file) $(bounds)
 targets += arch/$(SRCARCH)/kernel/asm-offsets.s
 clean-files := $(addprefix $(objtree)/,$(targets))
 
@@ -39,6 +40,23 @@ define cmd_offsets
 	 echo "#endif" ) > $@
 endef
 
+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" ) > $@
+endef
+
 # We use internal kbuild rules to avoid the "is up to date" message from make
 arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c FORCE
 	$(Q)mkdir -p $(dir $@)
@@ -48,6 +66,15 @@ $(obj)/$(offsets-file): arch/$(SRCARCH)/
 	$(Q)mkdir -p $(dir $@)
 	$(call cmd,offsets)
 
+# 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): kernel/bounds.s Kbuild
+	$(Q)mkdir -p $(dir $@)
+	$(call cmd,bounds)
+
 #####
 # 2) Check for missing system calls
 #
Index: linux-2.6/kernel/bounds.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/kernel/bounds.c	2008-02-29 19:29:38.000000000 -0800
@@ -0,0 +1,16 @@
+/*
+ * Generate definitions needed by the preprocessor.
+ * This code generates raw asm output which is post-processed
+ * to extract and format the required data.
+ */
+
+#include <linux/mm.h>
+
+#define DEFINE(sym, val) \
+        asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+
+#define BLANK() asm volatile("\n->" : : )
+
+void foo(void)
+{
+}
Index: linux-2.6/include/linux/bounds.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/include/linux/bounds.h	2008-02-29 19:29:50.000000000 -0800
@@ -0,0 +1,10 @@
+#ifndef __LINUX_BOUNDS_H__
+#define __LINUX_BOUNDS_H__
+/*
+ * DO NOT MODIFY.
+ *
+ * This file was generated by Kbuild
+ *
+ */
+
+#endif

-- 

  parent reply	other threads:[~2008-03-04  0:11 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-04  0:04 [rfc 00/10] [Patch] Page flags: Cleanup, reorg and introduce 5 new flags Christoph Lameter
2008-03-04  0:04 ` [rfc 01/10] Pageflags: Use an enum for the flags Christoph Lameter
2008-03-04  0:04 ` [rfc 02/10] Pageflags: Introduce macros to generate page flag functions Christoph Lameter
2008-03-04  0:04 ` [rfc 03/10] Pageflags: Convert to the use of new macros Christoph Lameter
2008-03-04  0:04 ` [rfc 04/10] Pageflags: Use proper page flag functions in Xen Christoph Lameter
2008-03-04  0:04 ` [rfc 05/10] Pageflags: Eliminate PG_xxx aliases Christoph Lameter
2008-03-04  0:04 ` [rfc 06/10] Sparsemem: Vmemmap does not need section bits Christoph Lameter
2008-03-04  0:04 ` Christoph Lameter [this message]
2008-03-04  0:05 ` [rfc 08/10] Pageflags: Get rid of FLAGS_RESERVED Christoph Lameter
2008-03-04  0:05 ` [rfc 09/10] Get rid of __ZONE_COUNT Christoph Lameter
2008-03-04  0:05 ` [rfc 10/10] Pageflags: Land grab Christoph Lameter
2008-03-04  1:27   ` Andi Kleen
2008-03-04  5:38     ` Christoph Lameter

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