2001-10-07 10:25:51

by Keith Owens

[permalink] [raw]
Subject: [patch] 2.4.11-pre4 remove spurious kernel recompiles

The kernel build dependency chain currently goes
Makefile ->
include/linux/version.h ->
340 sources and 66 .h files
The 66 .h files in turn infect almost every source, including anything
that includes module.h. The result is that changing a single character
in the top level Makefile forces a recompile of the entire kernel, for
no good reason.

The second problem is that version.h contains both UTS_RELEASE and
LINUX_VERSION_CODE. Changing the EXTRAVERSION field affects
UTS_RELEASE and again forces a massive recompile via version.h. This
is completely spurious, there are only 30 files that really care about
the full UTS_RELEASE field.

This patch removes the dependency on the top level Makefile and
seperates UTS_RELEASE from LINUX_VERSION_CODE. Changing the top level
Makefile no longer forces a complete recompile. Changing EXTRAVERSION
only affects a few files. Changing VERSION, PATCHLEVEL or SUBLEVEL
still does a major recompile, no way around that because of the number
of places that test LINUX_VERSION_CODE and modules that need the kernel
version string.

Note: This patch is not to be merged into Linus or AC trees yet, it
needs review first.

Index: 11-pre4.1/Makefile
--- 11-pre4.1/Makefile Fri, 05 Oct 2001 15:05:09 +1000 kaos (linux-2.4/T/c/50_Makefile 1.1.2.15.1.2.2.25.2.2.1.17.1.4.1.29 644)
+++ 11-pre4.1(w)/Makefile Sun, 07 Oct 2001 20:18:20 +1000 kaos (linux-2.4/T/c/50_Makefile 1.1.2.15.1.2.2.25.2.2.1.17.1.4.1.29 644)
@@ -212,7 +212,7 @@ CLEAN_DIRS = \

# files removed with 'make mrproper'
MRPROPER_FILES = \
- include/linux/autoconf.h include/linux/version.h \
+ include/linux/autoconf.h include/linux/version.h include/linux/uts_release.h \
drivers/net/hamradio/soundmodem/sm_tbl_{afsk1200,afsk2666,fsk9600}.h \
drivers/net/hamradio/soundmodem/sm_tbl_{hapn4800,psk4800}.h \
drivers/net/hamradio/soundmodem/sm_tbl_{afsk2400_7,afsk2400_8}.h \
@@ -255,7 +255,7 @@ Version: dummy
boot: vmlinux
@$(MAKE) CFLAGS="$(CFLAGS) $(CFLAGS_KERNEL)" -C arch/$(ARCH)/boot

-vmlinux: include/linux/version.h $(CONFIGURATION) init/main.o init/version.o linuxsubdirs
+vmlinux: include/linux/version.h include/linux/uts_release.h $(CONFIGURATION) init/main.o init/version.o linuxsubdirs
$(LD) $(LINKFLAGS) $(HEAD) init/main.o init/version.o \
--start-group \
$(CORE_FILES) \
@@ -280,7 +280,7 @@ xconfig: symlinks
$(MAKE) -C scripts kconfig.tk
wish -f scripts/kconfig.tk

-menuconfig: include/linux/version.h symlinks
+menuconfig: symlinks
$(MAKE) -C scripts/lxdialog all
$(CONFIG_SHELL) scripts/Menuconfig arch/$(ARCH)/config.in

@@ -293,16 +293,17 @@ include/config/MARKER: scripts/split-inc

linuxsubdirs: $(patsubst %, _dir_%, $(SUBDIRS))

-$(patsubst %, _dir_%, $(SUBDIRS)) : dummy include/linux/version.h include/config/MARKER
+$(patsubst %, _dir_%, $(SUBDIRS)) : dummy include/linux/version.h include/linux/uts_release.h include/config/MARKER
$(MAKE) CFLAGS="$(CFLAGS) $(CFLAGS_KERNEL)" -C $(patsubst _dir_%, %, $@)

$(TOPDIR)/include/linux/version.h: include/linux/version.h
+$(TOPDIR)/include/linux/uts_release.h: include/linux/uts_release.h
$(TOPDIR)/include/linux/compile.h: include/linux/compile.h

newversion:
. scripts/mkversion > .version

-include/linux/compile.h: $(CONFIGURATION) include/linux/version.h newversion
+include/linux/compile.h: $(CONFIGURATION) include/linux/version.h include/linux/uts_release.h newversion
@echo -n \#define UTS_VERSION \"\#`cat .version` > .ver
@if [ -n "$(CONFIG_SMP)" ] ; then echo -n " SMP" >> .ver; fi
@if [ -f .name ]; then echo -n \-`cat .name` >> .ver; fi
@@ -320,11 +321,17 @@ include/linux/compile.h: $(CONFIGURATION
@echo \#define LINUX_COMPILER \"`$(CC) $(CFLAGS) -v 2>&1 | tail -1`\" >> .ver
@mv -f .ver $@

-include/linux/version.h: ./Makefile
- @echo \#define UTS_RELEASE \"$(KERNELRELEASE)\" > .ver
- @echo \#define LINUX_VERSION_CODE `expr $(VERSION) \\* 65536 + $(PATCHLEVEL) \\* 256 + $(SUBLEVEL)` >> .ver
+include/linux/version.h: dummy
+ @rm -f .ver
+ @echo \#define LINUX_VERSION_CODE `expr $(VERSION) \\* 65536 + $(PATCHLEVEL) \\* 256 + $(SUBLEVEL)` > .ver
+ @echo \#define LINUX_VERSION_STRING \"$(VERSION).$(PATCHLEVEL).$(SUBLEVEL)\" >> .ver
@echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))' >>.ver
- @mv -f .ver $@
+ @cmp -s .ver $@ && rm .ver || mv -f .ver $@
+
+include/linux/uts_release.h: dummy
+ @rm -f .uts
+ @echo \#define UTS_RELEASE \"$(KERNELRELEASE)\" > .uts
+ @cmp -s .uts $@ && rm .uts || mv -f .uts $@

init/version.o: init/version.c include/linux/compile.h include/config/MARKER
$(CC) $(CFLAGS) $(CFLAGS_KERNEL) -DUTS_MACHINE='"$(ARCH)"' -c -o init/version.o init/version.c
@@ -356,7 +363,7 @@ endif
modules: $(patsubst %, _mod_%, $(SUBDIRS))

.PHONY: $(patsubst %, _mod_%, $(SUBDIRS))
-$(patsubst %, _mod_%, $(SUBDIRS)) : include/linux/version.h include/config/MARKER
+$(patsubst %, _mod_%, $(SUBDIRS)) : include/linux/version.h include/linux/uts_release.h include/config/MARKER
$(MAKE) -C $(patsubst _mod_%, %, $@) CFLAGS="$(CFLAGS) $(MODFLAGS)" MAKING_MODULES=1 modules

.PHONY: modules_install
@@ -449,7 +456,7 @@ htmldocs: sgmldocs
sums:
find . -type f -print | sort | xargs sum > .SUMS

-dep-files: scripts/mkdep archdep include/linux/version.h
+dep-files: scripts/mkdep archdep include/linux/version.h include/linux/uts_release.h
scripts/mkdep -- init/*.c > .depend
scripts/mkdep -- `find $(FINDHPATH) -name SCCS -prune -o -follow -name \*.h ! -name modversions.h -print` > .hdepend
$(MAKE) $(patsubst %,_sfdep_%,$(SUBDIRS)) _FASTDEP_ALL_SUB_DIRS="$(SUBDIRS)"
Index: 11-pre4.1/init/version.c
--- 11-pre4.1/init/version.c Fri, 05 Jan 2001 13:42:29 +1100 kaos (linux-2.4/k/10_version.c 1.1 644)
+++ 11-pre4.1(w)/init/version.c Sun, 07 Oct 2001 19:33:49 +1000 kaos (linux-2.4/k/10_version.c 1.1 644)
@@ -9,6 +9,7 @@
#include <linux/uts.h>
#include <linux/utsname.h>
#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/compile.h>

#define version(a) Version_ ## a
Index: 11-pre4.1/include/asm-parisc/linux_logo.h
--- 11-pre4.1/include/asm-parisc/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/l/18_linux_logo 1.1.2.1 644)
+++ 11-pre4.1(w)/include/asm-parisc/linux_logo.h Sun, 07 Oct 2001 19:33:52 +1000 kaos (linux-2.4/l/18_linux_logo 1.1.2.1 644)
@@ -19,7 +19,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/PA-RISC version " UTS_RELEASE

Index: 11-pre4.1/include/asm-mips64/linux_logo.h
--- 11-pre4.1/include/asm-mips64/linux_logo.h Mon, 10 Sep 2001 15:46:51 +1000 kaos (linux-2.4/p/29_linux_logo 1.1.2.1.1.1 644)
+++ 11-pre4.1(w)/include/asm-mips64/linux_logo.h Sun, 07 Oct 2001 19:33:55 +1000 kaos (linux-2.4/p/29_linux_logo 1.1.2.1.1.1 644)
@@ -19,7 +19,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/MIPS64 version " UTS_RELEASE

Index: 11-pre4.1/include/asm-ia64/linux_logo.h
--- 11-pre4.1/include/asm-ia64/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/t/18_linux_logo 1.1.2.1 644)
+++ 11-pre4.1(w)/include/asm-ia64/linux_logo.h Sun, 07 Oct 2001 19:33:57 +1000 kaos (linux-2.4/t/18_linux_logo 1.1.2.1 644)
@@ -20,7 +20,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/ia64 version " UTS_RELEASE

Index: 11-pre4.1/include/asm-sh/linux_logo.h
--- 11-pre4.1/include/asm-sh/linux_logo.h Sun, 09 Sep 2001 19:22:07 +1000 kaos (linux-2.4/u/37_linux_logo 1.1.2.2 644)
+++ 11-pre4.1(w)/include/asm-sh/linux_logo.h Sun, 07 Oct 2001 19:33:59 +1000 kaos (linux-2.4/u/37_linux_logo 1.1.2.2 644)
@@ -20,7 +20,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/SuperH version " UTS_RELEASE

Index: 11-pre4.1/include/asm-arm/linux_logo.h
--- 11-pre4.1/include/asm-arm/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/z/42_linux_logo 1.2.1.1 644)
+++ 11-pre4.1(w)/include/asm-arm/linux_logo.h Sun, 07 Oct 2001 19:34:02 +1000 kaos (linux-2.4/z/42_linux_logo 1.2.1.1 644)
@@ -11,7 +11,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "ARM Linux version " UTS_RELEASE

Index: 11-pre4.1/include/asm-sparc64/linux_logo.h
--- 11-pre4.1/include/asm-sparc64/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/C/49_linux_logo 1.1.2.1 644)
+++ 11-pre4.1(w)/include/asm-sparc64/linux_logo.h Sun, 07 Oct 2001 19:34:04 +1000 kaos (linux-2.4/C/49_linux_logo 1.1.2.1 644)
@@ -19,7 +19,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/UltraSPARC version " UTS_RELEASE

Index: 11-pre4.1/include/asm-ppc/linux_logo.h
--- 11-pre4.1/include/asm-ppc/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/F/46_linux_logo 1.2.1.2 644)
+++ 11-pre4.1(w)/include/asm-ppc/linux_logo.h Sun, 07 Oct 2001 19:34:58 +1000 kaos (linux-2.4/F/46_linux_logo 1.2.1.2 644)
@@ -16,6 +16,7 @@
#ifdef __KERNEL__

#include <linux/init.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/PPC version " UTS_RELEASE

Index: 11-pre4.1/include/asm-sparc/linux_logo.h
--- 11-pre4.1/include/asm-sparc/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/J/34_linux_logo 1.1.2.1 644)
+++ 11-pre4.1(w)/include/asm-sparc/linux_logo.h Sun, 07 Oct 2001 19:35:01 +1000 kaos (linux-2.4/J/34_linux_logo 1.1.2.1 644)
@@ -19,7 +19,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/SPARC version " UTS_RELEASE

Index: 11-pre4.1/include/asm-m68k/linux_logo.h
--- 11-pre4.1/include/asm-m68k/linux_logo.h Wed, 13 Jun 2001 12:08:44 +1000 kaos (linux-2.4/O/14_linux_logo 1.1.2.2 644)
+++ 11-pre4.1(w)/include/asm-m68k/linux_logo.h Sun, 07 Oct 2001 19:35:03 +1000 kaos (linux-2.4/O/14_linux_logo 1.1.2.2 644)
@@ -20,7 +20,7 @@

#include <linux/config.h>
#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/m68k version " UTS_RELEASE

Index: 11-pre4.1/include/asm-alpha/linux_logo.h
--- 11-pre4.1/include/asm-alpha/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/P/2_linux_logo 1.1.2.1 644)
+++ 11-pre4.1(w)/include/asm-alpha/linux_logo.h Sun, 07 Oct 2001 19:35:08 +1000 kaos (linux-2.4/P/2_linux_logo 1.1.2.1 644)
@@ -19,7 +19,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/AXP version " UTS_RELEASE

Index: 11-pre4.1/include/asm-i386/linux_logo.h
--- 11-pre4.1/include/asm-i386/linux_logo.h Sat, 09 Jun 2001 11:25:53 +1000 kaos (linux-2.4/T/44_linux_logo 1.1.2.1 644)
+++ 11-pre4.1(w)/include/asm-i386/linux_logo.h Sun, 07 Oct 2001 19:35:26 +1000 kaos (linux-2.4/T/44_linux_logo 1.1.2.1 644)
@@ -19,7 +19,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#define linux_logo_banner "Linux/ia32 version " UTS_RELEASE

Index: 11-pre4.1/include/linux/module.h
--- 11-pre4.1/include/linux/module.h Thu, 04 Oct 2001 16:23:36 +1000 kaos (linux-2.4/c/b/46_module.h 1.1.1.1.2.5 644)
+++ 11-pre4.1(w)/include/linux/module.h Sun, 07 Oct 2001 19:47:04 +1000 kaos (linux-2.4/c/b/46_module.h 1.1.1.1.2.5 644)
@@ -298,7 +298,7 @@ extern struct module __this_module;

#include <linux/version.h>
static const char __module_kernel_version[] __attribute__((section(".modinfo"))) =
-"kernel_version=" UTS_RELEASE;
+"kernel_version=" LINUX_VERSION_STRING;
#ifdef MODVERSIONS
static const char __module_using_checksums[] __attribute__((section(".modinfo"))) =
"using_checksums=1";
Index: 11-pre4.1/drivers/cdrom/mcdx.c
--- 11-pre4.1/drivers/cdrom/mcdx.c Sat, 08 Sep 2001 14:40:18 +1000 kaos (linux-2.4/L/b/23_mcdx.c 1.3.1.1 644)
+++ 11-pre4.1(w)/drivers/cdrom/mcdx.c Sun, 07 Oct 2001 19:35:35 +1000 kaos (linux-2.4/L/b/23_mcdx.c 1.3.1.1 644)
@@ -56,7 +56,7 @@ static const char *mcdx_c_version
= "$Id$";
#endif

-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/module.h>

#include <linux/errno.h>
Index: 11-pre4.1/drivers/cdrom/aztcd.c
--- 11-pre4.1/drivers/cdrom/aztcd.c Mon, 10 Sep 2001 15:46:51 +1000 kaos (linux-2.4/L/b/28_aztcd.c 1.1.1.2 644)
+++ 11-pre4.1(w)/drivers/cdrom/aztcd.c Sun, 07 Oct 2001 19:35:38 +1000 kaos (linux-2.4/L/b/28_aztcd.c 1.1.1.2 644)
@@ -165,7 +165,7 @@
Torben Mathiasen <[email protected]>
*/

-#include <linux/version.h>
+#include <linux/uts_release.h>

#define MAJOR_NR AZTECH_CDROM_MAJOR

Index: 11-pre4.1/drivers/scsi/megaraid.c
--- 11-pre4.1/drivers/scsi/megaraid.c Tue, 02 Oct 2001 11:04:33 +1000 kaos (linux-2.4/Q/b/35_megaraid.c 1.2.1.5.1.3.1.3 644)
+++ 11-pre4.1(w)/drivers/scsi/megaraid.c Sun, 07 Oct 2001 19:37:54 +1000 kaos (linux-2.4/Q/b/35_megaraid.c 1.2.1.5.1.3.1.3 644)
@@ -452,6 +452,7 @@

#include <linux/config.h>
#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
Index: 11-pre4.1/drivers/char/ftape/zftape/zftape-init.c
--- 11-pre4.1/drivers/char/ftape/zftape/zftape-init.c Fri, 14 Sep 2001 12:20:01 +1000 kaos (linux-2.4/Z/b/49_zftape-ini 1.2.1.1 644)
+++ 11-pre4.1(w)/drivers/char/ftape/zftape/zftape-init.c Sun, 07 Oct 2001 19:39:24 +1000 kaos (linux-2.4/Z/b/49_zftape-ini 1.2.1.1 644)
@@ -23,7 +23,7 @@
#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/fs.h>
#include <asm/segment.h>
#include <linux/kernel.h>
Index: 11-pre4.1/drivers/char/ftape/lowlevel/ftape-init.c
--- 11-pre4.1/drivers/char/ftape/lowlevel/ftape-init.c Fri, 14 Sep 2001 12:20:01 +1000 kaos (linux-2.4/a/c/39_ftape-init 1.1.1.1 644)
+++ 11-pre4.1(w)/drivers/char/ftape/lowlevel/ftape-init.c Sun, 07 Oct 2001 19:39:27 +1000 kaos (linux-2.4/a/c/39_ftape-init 1.1.1.1 644)
@@ -24,6 +24,7 @@
#include <linux/config.h>
#include <linux/module.h>
#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
Index: 11-pre4.1/drivers/char/ftape/compressor/zftape-compress.c
--- 11-pre4.1/drivers/char/ftape/compressor/zftape-compress.c Fri, 14 Sep 2001 12:20:01 +1000 kaos (linux-2.4/a/c/42_zftape-com 1.1.1.1 644)
+++ 11-pre4.1(w)/drivers/char/ftape/compressor/zftape-compress.c Sun, 07 Oct 2001 19:39:29 +1000 kaos (linux-2.4/a/c/42_zftape-com 1.1.1.1 644)
@@ -34,6 +34,7 @@
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/uts_release.h>

#include <linux/zftape.h>

Index: 11-pre4.1/drivers/block/floppy.c
--- 11-pre4.1/drivers/block/floppy.c Tue, 11 Sep 2001 11:19:14 +1000 kaos (linux-2.4/c/c/40_floppy.c 1.2.1.1.1.2 644)
+++ 11-pre4.1(w)/drivers/block/floppy.c Sun, 07 Oct 2001 19:39:36 +1000 kaos (linux-2.4/c/c/40_floppy.c 1.2.1.1.1.2 644)
@@ -147,6 +147,7 @@ static int print_unex=1;
#include <linux/tqueue.h>
#define FDPATCHES
#include <linux/fdreg.h>
+#include <linux/uts_release.h>

/*
* 1998/1/21 -- Richard Gooch <[email protected]> -- devfs support
Index: 11-pre4.1/arch/ppc/kernel/chrp_setup.c
--- 11-pre4.1/arch/ppc/kernel/chrp_setup.c Sun, 09 Sep 2001 19:22:07 +1000 kaos (linux-2.4/I/c/36_chrp_setup 1.3.1.2.1.5.1.3 644)
+++ 11-pre4.1(w)/arch/ppc/kernel/chrp_setup.c Sun, 07 Oct 2001 19:39:43 +1000 kaos (linux-2.4/I/c/36_chrp_setup 1.3.1.2.1.5.1.3 644)
@@ -33,7 +33,7 @@
#include <linux/ioport.h>
#include <linux/console.h>
#include <linux/pci.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/adb.h>
#include <linux/module.h>
#include <linux/delay.h>
Index: 11-pre4.1/arch/alpha/boot/bootp.c
--- 11-pre4.1/arch/alpha/boot/bootp.c Fri, 05 Oct 2001 15:05:09 +1000 kaos (linux-2.4/R/c/26_bootp.c 1.2 644)
+++ 11-pre4.1(w)/arch/alpha/boot/bootp.c Sun, 07 Oct 2001 19:40:18 +1000 kaos (linux-2.4/R/c/26_bootp.c 1.2 644)
@@ -9,7 +9,7 @@
*/
#include <linux/kernel.h>
#include <linux/string.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/mm.h>

#include <asm/system.h>
Index: 11-pre4.1/arch/alpha/boot/main.c
--- 11-pre4.1/arch/alpha/boot/main.c Fri, 05 Jan 2001 13:42:29 +1100 kaos (linux-2.4/R/c/30_main.c 1.1 644)
+++ 11-pre4.1(w)/arch/alpha/boot/main.c Sun, 07 Oct 2001 19:40:21 +1000 kaos (linux-2.4/R/c/30_main.c 1.1 644)
@@ -7,7 +7,7 @@
*/
#include <linux/kernel.h>
#include <linux/string.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/mm.h>

#include <asm/system.h>
Index: 11-pre4.1/arch/i386/boot/setup.S
--- 11-pre4.1/arch/i386/boot/setup.S Tue, 07 Aug 2001 18:58:36 +1000 kaos (linux-2.4/T/c/45_setup.S 1.1.1.3.1.1 644)
+++ 11-pre4.1(w)/arch/i386/boot/setup.S Sun, 07 Oct 2001 19:40:25 +1000 kaos (linux-2.4/T/c/45_setup.S 1.1.1.3.1.1 644)
@@ -46,7 +46,7 @@

#include <linux/config.h>
#include <asm/segment.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/compile.h>
#include <asm/boot.h>
#include <asm/e820.h>
Index: 11-pre4.1/drivers/s390/block/xpram.c
--- 11-pre4.1/drivers/s390/block/xpram.c Tue, 11 Sep 2001 11:19:14 +1000 kaos (linux-2.4/q/d/42_xpram.c 1.2.1.3 644)
+++ 11-pre4.1(w)/drivers/s390/block/xpram.c Sun, 07 Oct 2001 19:35:32 +1000 kaos (linux-2.4/q/d/42_xpram.c 1.2.1.3 644)
@@ -57,6 +57,7 @@

#include <linux/module.h>
#include <linux/version.h>
+#include <linux/uts_release.h>

#ifdef MODULE
char kernel_version [] = UTS_RELEASE;
Index: 11-pre4.1/drivers/scsi/aic7xxx_old.c
--- 11-pre4.1/drivers/scsi/aic7xxx_old.c Tue, 02 Oct 2001 11:04:33 +1000 kaos (linux-2.4/y/d/26_aic7xxx_ol 1.9 644)
+++ 11-pre4.1(w)/drivers/scsi/aic7xxx_old.c Sun, 07 Oct 2001 19:39:12 +1000 kaos (linux-2.4/y/d/26_aic7xxx_ol 1.9 644)
@@ -232,6 +232,7 @@
#include <asm/irq.h>
#include <asm/byteorder.h>
#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/kernel.h>
Index: 11-pre4.1/arch/ppc/kernel/btext.c
--- 11-pre4.1/arch/ppc/kernel/btext.c Sun, 09 Sep 2001 19:22:07 +1000 kaos (linux-2.4/h/f/32_btext.c 1.2 644)
+++ 11-pre4.1(w)/arch/ppc/kernel/btext.c Sun, 07 Oct 2001 19:39:46 +1000 kaos (linux-2.4/h/f/32_btext.c 1.2 644)
@@ -10,7 +10,7 @@
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>

#include <asm/sections.h>
#include <asm/bootx.h>
Index: 11-pre4.1/include/asm-mips/linux_logo_sgi.h
--- 11-pre4.1/include/asm-mips/linux_logo_sgi.h Mon, 10 Sep 2001 15:46:51 +1000 kaos (linux-2.4/m/f/1_linux_logo 1.1 644)
+++ 11-pre4.1(w)/include/asm-mips/linux_logo_sgi.h Sun, 07 Oct 2001 19:35:12 +1000 kaos (linux-2.4/m/f/1_linux_logo 1.1 644)
@@ -10,7 +10,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/config.h>

#define linux_logo_banner "Linux/MIPS version " UTS_RELEASE
Index: 11-pre4.1/include/asm-mips/linux_logo_dec.h
--- 11-pre4.1/include/asm-mips/linux_logo_dec.h Mon, 10 Sep 2001 15:46:51 +1000 kaos (linux-2.4/m/f/2_linux_logo 1.1 644)
+++ 11-pre4.1(w)/include/asm-mips/linux_logo_dec.h Sun, 07 Oct 2001 19:35:23 +1000 kaos (linux-2.4/m/f/2_linux_logo 1.1 644)
@@ -10,7 +10,7 @@
*/

#include <linux/init.h>
-#include <linux/version.h>
+#include <linux/uts_release.h>
#include <linux/config.h>

#define linux_logo_banner "Linux/MIPSel version " UTS_RELEASE


2001-10-07 18:05:51

by Andrea Arcangeli

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Sun, Oct 07, 2001 at 08:25:42PM +1000, Keith Owens wrote:
> in the top level Makefile forces a recompile of the entire kernel, for
> no good reason.

this is a matter of taste but personally I believe that at least
theorically recompiling the whole kernel if I add -g to CFLAGS, or if I
change the EXTRAVERSION have lots of sense. OTOH at the moment I
wouldn't trust the buildsystem anyways, so I'd run a `make distclean`
anyways in those cases :).

Andrea

2001-10-07 18:16:31

by Jeff Garzik

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Sun, 7 Oct 2001, Andrea Arcangeli wrote:

> On Sun, Oct 07, 2001 at 08:25:42PM +1000, Keith Owens wrote:
> > in the top level Makefile forces a recompile of the entire kernel, for
> > no good reason.
>
> this is a matter of taste but personally I believe that at least
> theorically recompiling the whole kernel if I add -g to CFLAGS, or if I
> change the EXTRAVERSION have lots of sense.

Correct. I am amazed Keith missed this... changing data in Makefile
can certainly affect the entire kernel compile, so it makes sense to
recompile the entire kernel when it changes.

If we want to change this, one must isolate the specific changes which
cause the entire kernel (or just init/main.c) to be recompiled, and
put those in a separate file.


> OTOH at the moment I
> wouldn't trust the buildsystem anyways, so I'd run a `make distclean`
> anyways in those cases :).

ditto :) my kbuild script looks basically like:

make distclean && cp <kconfig dir>/rum .config && make oldconfig &&
make oldconfig && make -j3 dep && make -j3 && make modules && make boot

Jeff



2001-10-07 23:29:08

by Keith Owens

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Sun, 7 Oct 2001 13:16:19 -0500 (CDT),
Jeff Garzik <[email protected]> wrote:
>On Sun, 7 Oct 2001, Andrea Arcangeli wrote:
>
>> On Sun, Oct 07, 2001 at 08:25:42PM +1000, Keith Owens wrote:
>> > in the top level Makefile forces a recompile of the entire kernel, for
>> > no good reason.
>>
>> this is a matter of taste but personally I believe that at least
>> theorically recompiling the whole kernel if I add -g to CFLAGS, or if I
>> change the EXTRAVERSION have lots of sense.
>
>Correct. I am amazed Keith missed this... changing data in Makefile
>can certainly affect the entire kernel compile, so it makes sense to
>recompile the entire kernel when it changes.

I did not miss it. Changing cflags is detected by the
.<object>.o.flags files.

ifeq (-D__KERNEL__ -I/build/kaos/2.4.11-pre4/include -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fomit-frame-pointer -fno-strict-aliasing -fno-common -pipe -mpreferred-stack-boundary=2 -march=i586,$(strip $(subst $(comma),:,$(CFLAGS) $(EXTRA_CFLAGS) $(CFLAGS_vt.o))))
FILES_FLAGS_UP_TO_DATE += vt.o
endif

kbuild already detects changes to flags, down to the level of
per-object flags, there is no need to detect changes to the top level
Makefile. Especially when you can override flags and other fields on
the make command line, that does not change Makefile but kbuild still
detects the changes.

2001-10-08 00:07:04

by Andrea Arcangeli

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Mon, Oct 08, 2001 at 09:29:06AM +1000, Keith Owens wrote:
> On Sun, 7 Oct 2001 13:16:19 -0500 (CDT),
> Jeff Garzik <[email protected]> wrote:
> >On Sun, 7 Oct 2001, Andrea Arcangeli wrote:
> >
> >> On Sun, Oct 07, 2001 at 08:25:42PM +1000, Keith Owens wrote:
> >> > in the top level Makefile forces a recompile of the entire kernel, for
> >> > no good reason.
> >>
> >> this is a matter of taste but personally I believe that at least
> >> theorically recompiling the whole kernel if I add -g to CFLAGS, or if I
> >> change the EXTRAVERSION have lots of sense.
> >
> >Correct. I am amazed Keith missed this... changing data in Makefile
> >can certainly affect the entire kernel compile, so it makes sense to
> >recompile the entire kernel when it changes.
>
> I did not miss it. Changing cflags is detected by the
> .<object>.o.flags files.
>
> ifeq (-D__KERNEL__ -I/build/kaos/2.4.11-pre4/include -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fomit-frame-pointer -fno-strict-aliasing -fno-common -pipe -mpreferred-stack-boundary=2 -march=i586,$(strip $(subst $(comma),:,$(CFLAGS) $(EXTRA_CFLAGS) $(CFLAGS_vt.o))))
> FILES_FLAGS_UP_TO_DATE += vt.o
> endif

Ok, so the point of all those .flags is to catch per-object cflags changes.

> kbuild already detects changes to flags, down to the level of
> per-object flags, there is no need to detect changes to the top level
> Makefile. Especially when you can override flags and other fields on
> the make command line, that does not change Makefile but kbuild still
> detects the changes.

CFLAGS was only an example, think if I change CC or EXTRAVERSION, but, as
said in the earlier email, I doubt an EXTRAVERSION change would work
without a full distclean in between anyways.

Andrea

2001-10-08 00:42:58

by Keith Owens

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Mon, 8 Oct 2001 02:05:44 +0200,
Andrea Arcangeli <[email protected]> wrote:
>On Mon, Oct 08, 2001 at 09:29:06AM +1000, Keith Owens wrote:
>> I did not miss it. Changing cflags is detected by the
>> .<object>.o.flags files.
>>
>> ifeq (-D__KERNEL__ -I/build/kaos/2.4.11-pre4/include -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fomit-frame-pointer -fno-strict-aliasing -fno-common -pipe -mpreferred-stack-boundary=2 -march=i586,$(strip $(subst $(comma),:,$(CFLAGS) $(EXTRA_CFLAGS) $(CFLAGS_vt.o))))
>> FILES_FLAGS_UP_TO_DATE += vt.o
>> endif
>
>Ok, so the point of all those .flags is to catch per-object cflags changes.

It catches all cflags changes, from global CFLAGS, per directory cflags
and per object cflags. I repeat, you do not need to detect changes to
the top level Makefile in order to detect cflag changes.

>CFLAGS was only an example, think if I change CC or EXTRAVERSION, but, as
>said in the earlier email, I doubt an EXTRAVERSION change would work
>without a full distclean in between anyways.

Of course it works. EXTRAVERSION is only a human readable string used
by 15 sources (via UTS_RELEASE) and by the various logo.h files.
Changing EXTRAVERSION has no effect on executable code, it only affects
display fields. Any other files changed at the same time as
EXTRAVERSION (say by a patch) will be recompiled, based on the
timestamp changes. Adding a patch which changes EXTRAVERSION does not
require a full recompile, which is why the existing system is broken.

I admit that kbuild 2.4 does not correctly handle changes to CC, if you
"make CC=gcc" then "make CC=kgcc", the kernel is not rebuilt. You must
manually make distlean or mrproper when changing CC. Note that
overriding flags on the command line does not change the Makefile so
you cannot rely on the Makefile timestamp to detect command changes,

IOW a check for Makefile timestamp is both overkill (it recompiles too
much) and incomplete (it does not detect command line overrides). BTW,
kbuild 2.5 gets this right.

module.h currently uses the full UTS_RELEASE which includes
EXTRAVERSION but that is spurious, modutils ignores EXTRAVERSION when
loading a module. modutils only cares about VERSION, PATCHLEVEL and
SUBLEVEL.

2001-10-08 01:21:04

by Andrea Arcangeli

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Mon, Oct 08, 2001 at 10:42:56AM +1000, Keith Owens wrote:
> On Mon, 8 Oct 2001 02:05:44 +0200,
> Andrea Arcangeli <[email protected]> wrote:
> >On Mon, Oct 08, 2001 at 09:29:06AM +1000, Keith Owens wrote:
> >> I did not miss it. Changing cflags is detected by the
> >> .<object>.o.flags files.
> >>
> >> ifeq (-D__KERNEL__ -I/build/kaos/2.4.11-pre4/include -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fomit-frame-pointer -fno-strict-aliasing -fno-common -pipe -mpreferred-stack-boundary=2 -march=i586,$(strip $(subst $(comma),:,$(CFLAGS) $(EXTRA_CFLAGS) $(CFLAGS_vt.o))))
> >> FILES_FLAGS_UP_TO_DATE += vt.o
> >> endif
> >
> >Ok, so the point of all those .flags is to catch per-object cflags changes.
>
> It catches all cflags changes, from global CFLAGS, per directory cflags
> and per object cflags. I repeat, you do not need to detect changes to
> the top level Makefile in order to detect cflag changes.

Sure I understand that.

> >CFLAGS was only an example, think if I change CC or EXTRAVERSION, but, as
> >said in the earlier email, I doubt an EXTRAVERSION change would work
> >without a full distclean in between anyways.
>
> Of course it works. EXTRAVERSION is only a human readable string used
> by 15 sources (via UTS_RELEASE) and by the various logo.h files.
> Changing EXTRAVERSION has no effect on executable code, it only affects
> display fields. Any other files changed at the same time as
> EXTRAVERSION (say by a patch) will be recompiled, based on the
> timestamp changes. Adding a patch which changes EXTRAVERSION does not
> require a full recompile, which is why the existing system is broken.

I didn't expected it to work including module versioning without a full
recompile, but good to know.

> I admit that kbuild 2.4 does not correctly handle changes to CC, if you
> "make CC=gcc" then "make CC=kgcc", the kernel is not rebuilt. You must
> manually make distlean or mrproper when changing CC. Note that
> overriding flags on the command line does not change the Makefile so
> you cannot rely on the Makefile timestamp to detect command changes,
>
> IOW a check for Makefile timestamp is both overkill (it recompiles too
> much) and incomplete (it does not detect command line overrides). BTW,
> kbuild 2.5 gets this right.

That sounds fine. Of course the only regression could be the build time.
Do you have a benchmark on the build time with kbuild 2.5 applied to
2.4.10 compared to the build time of 2.4.10?

>
> module.h currently uses the full UTS_RELEASE which includes
> EXTRAVERSION but that is spurious, modutils ignores EXTRAVERSION when
> loading a module. modutils only cares about VERSION, PATCHLEVEL and
> SUBLEVEL.

Well again EXTRAVERSION was just an example, SUBLEVEL was the same
problem as EXTRAVERSION for me, I mean after you apply an -ac patch that
for example goes backwards in the SUBLEVEL, do you recompile everything
or do you just run make after your Makefile patch is applied to the
kernel?

Andrea

2001-10-08 01:34:04

by Keith Owens

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Mon, 8 Oct 2001 03:20:23 +0200,
Andrea Arcangeli <[email protected]> wrote:
>On Mon, Oct 08, 2001 at 10:42:56AM +1000, Keith Owens wrote:
>> IOW a check for Makefile timestamp is both overkill (it recompiles too
>> much) and incomplete (it does not detect command line overrides). BTW,
>> kbuild 2.5 gets this right.
>
>That sounds fine. Of course the only regression could be the build time.
>Do you have a benchmark on the build time with kbuild 2.5 applied to
>2.4.10 compared to the build time of 2.4.10?

kbuild 2.5 build times vary from 10% faster to 100% slower, depending
on the number of objects being compiled. There are some O(n^2)
algorithms in kbuild 2.5, I know where they are and how to fix them, it
just takes time that I don't have right now. At the moment I am
concentrating on correctness for kbuild 2.5. MEC mantra:

Correctness comes first.
Then maintainability.
Then speed.

>> module.h currently uses the full UTS_RELEASE which includes
>> EXTRAVERSION but that is spurious, modutils ignores EXTRAVERSION when
>> loading a module. modutils only cares about VERSION, PATCHLEVEL and
>> SUBLEVEL.
>
>Well again EXTRAVERSION was just an example, SUBLEVEL was the same
>problem as EXTRAVERSION for me, I mean after you apply an -ac patch that
>for example goes backwards in the SUBLEVEL, do you recompile everything
>or do you just run make after your Makefile patch is applied to the
>kernel?

Changing VERSION, PATCHLEVEL or SUBLEVEL requires a recompile of
anything that tests LINUX_VERSION_CODE, including everything that
includes module.h. That already occurs because the timestamp of
include/linux/version.h changes. I pointed this out in the patch
notes.

My patch to the Makefile does not (cannot) change the dependencies on
LINUX_VERSION_CODE. I am removing the spurious recompiles caused by
changing EXTRAVERSION and by changing lines in the top level Makefile
that do not directly affect objects. With my patch only the required
objects are rebuilt.

BTW, how can you apply a -ac patch that sets SUBLEVEL backwards? -ac
patches are against the Linus tree with the same VERSION, PATCHLEVEL
and SUBLEVEL.

2001-10-08 02:12:56

by Andrea Arcangeli

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Mon, Oct 08, 2001 at 11:34:04AM +1000, Keith Owens wrote:
> On Mon, 8 Oct 2001 03:20:23 +0200,
> Andrea Arcangeli <[email protected]> wrote:
> >On Mon, Oct 08, 2001 at 10:42:56AM +1000, Keith Owens wrote:
> >> IOW a check for Makefile timestamp is both overkill (it recompiles too
> >> much) and incomplete (it does not detect command line overrides). BTW,
> >> kbuild 2.5 gets this right.
> >
> >That sounds fine. Of course the only regression could be the build time.
> >Do you have a benchmark on the build time with kbuild 2.5 applied to
> >2.4.10 compared to the build time of 2.4.10?
>
> kbuild 2.5 build times vary from 10% faster to 100% slower, depending
> on the number of objects being compiled. There are some O(n^2)

I meant for a stright compile, which is going to be its worst case and
my common case.

The main thing I like is to be able to compile out of the tree and
avoiding touching the header files during compilation (that's really
annoying).

> algorithms in kbuild 2.5, I know where they are and how to fix them, it
> just takes time that I don't have right now. At the moment I am
> concentrating on correctness for kbuild 2.5. MEC mantra:
>
> Correctness comes first.
> Then maintainability.
> Then speed.

I personally don't care about correctness in the sense of getting "make"
doing everything for you regardless of what you changed, I'm fine with
some "make distclean" forced checkpoint after PATCHLEVEL changed etc...,
you said infact full compile is needed sometime, not to tell about
kernel configuration.

One good example is the mkdep hack, it's far from correct: the header
dependences is nearly random. We cannot trust it unless we remeber
every user included us (one more reason I'm used to full recompiles),
but it's much faster than the correct full dependences generated by gcc
so I'm fine with it. When I compile other projects like kde2 I'm amazed
how slow the compilation is, ok it's not stright C but I bet the
correctness of its dependences hits a lot too on the compilation time
(but it's rebuilt in background so I don't care if it's slow while for
the kernel I'm sometime more synchronous waiting for the compilation to
finish :).

> BTW, how can you apply a -ac patch that sets SUBLEVEL backwards? -ac

First backout Linus's pre patch, then apply AC's -ac. The end result is
a backwards SUBLEVEL.

Andrea

2001-10-08 02:49:28

by Keith Owens

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Mon, 8 Oct 2001 04:12:15 +0200,
Andrea Arcangeli <[email protected]> wrote:
>On Mon, Oct 08, 2001 at 11:34:04AM +1000, Keith Owens wrote:
>The main thing I like is to be able to compile out of the tree and
>avoiding touching the header files during compilation (that's really
>annoying).

All fixed in kbuild 2.5.

>I personally don't care about correctness in the sense of getting "make"
>doing everything for you regardless of what you changed, I'm fine with
>some "make distclean" forced checkpoint after PATCHLEVEL changed etc...,
>you said infact full compile is needed sometime, not to tell about
>kernel configuration.

Strongly disagree. One of the biggest problems with kbuild is the user
who applies a patch and expects the kernel to automatically rebuild
just the bits that are affected. We must not rely on every user doing
make distclean or mrproper after applying a patch, we know that does
not happen, resulting in inconsistent kernels. If you want to do a
complete recompile after a patch that is your choice, but we cannot
rely on the entire user population doing that. kbuild must be
automatic and correct.

>One good example is the mkdep hack, it's far from correct: the header
>dependences is nearly random. We cannot trust it unless we remeber
>every user included us (one more reason I'm used to full recompiles),

Absolutely agree. The design assumption for mkdep is that the source
and/or .config do not change after make dep. That might have been true
once but with several kernel trees, separate arch patches, separate sub
system patches and compiling for multiple configurations it is not true
now. kbuild 2.5 completely redesigned the dependency tree and gets it
right!

However we are getting off the original patch which removes spurious
compiles from the existing system.

2001-10-08 03:08:14

by Andrea Arcangeli

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

On Mon, Oct 08, 2001 at 12:49:25PM +1000, Keith Owens wrote:
> On Mon, 8 Oct 2001 04:12:15 +0200,
> Andrea Arcangeli <[email protected]> wrote:
> >On Mon, Oct 08, 2001 at 11:34:04AM +1000, Keith Owens wrote:
> >The main thing I like is to be able to compile out of the tree and
> >avoiding touching the header files during compilation (that's really
> >annoying).
>
> All fixed in kbuild 2.5.

Of course I know, this is why I mentioned it :) That's most exiting
thing from my point of view.

> >I personally don't care about correctness in the sense of getting "make"
> >doing everything for you regardless of what you changed, I'm fine with
> >some "make distclean" forced checkpoint after PATCHLEVEL changed etc...,
> >you said infact full compile is needed sometime, not to tell about
> >kernel configuration.
>
> Strongly disagree. One of the biggest problems with kbuild is the user
> who applies a patch and expects the kernel to automatically rebuild
> just the bits that are affected. We must not rely on every user doing
> make distclean or mrproper after applying a patch, we know that does
> not happen, resulting in inconsistent kernels. If you want to do a
> complete recompile after a patch that is your choice, but we cannot

As everybody out there I have to evaluate every time if a recompile is
needed or not in function of the patch. Not a big deal.

But for mixed collection of patches like pre-patches or -ac, I don't
care, I just recompile the whole thing since it's unlikely I can trust
the build system to do everything right (mkdep problem for example) and
there are usually too many changes to save a rasonable amount of
compile time anyways.

> rely on the entire user population doing that. kbuild must be
> automatic and correct.

If it's fast as well I'm fine of course :) But waiting the double of the
time isn't an obvious improvement for me, note that when the SUBLEVEL
changes all modules have to be recompiled at least, and so the smarter
buildsystem cannot take advantage of the fact the module sourcecode
didn't changed, and a small change in the include files can have a large
impact of the rebuild percentage etc...

> >One good example is the mkdep hack, it's far from correct: the header
> >dependences is nearly random. We cannot trust it unless we remeber
> >every user included us (one more reason I'm used to full recompiles),
>
> Absolutely agree. The design assumption for mkdep is that the source
> and/or .config do not change after make dep. That might have been true
> once but with several kernel trees, separate arch patches, separate sub
> system patches and compiling for multiple configurations it is not true
> now. kbuild 2.5 completely redesigned the dependency tree and gets it
> right!

The mkdep logic (seen as "not going deeper than the explicit #include")
is quite orthogonal with the separate tree issue, you could build the
current .depend tree outside the kernel source tree too, that wouldn't
be a problem.

> However we are getting off the original patch which removes spurious
> compiles from the existing system.

Indeed :).

Andrea

2001-10-08 16:19:06

by Bill Davidsen

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

In article <[email protected]> [email protected] wrote:

| This patch removes the dependency on the top level Makefile and
| seperates UTS_RELEASE from LINUX_VERSION_CODE. Changing the top level
| Makefile no longer forces a complete recompile. Changing EXTRAVERSION
| only affects a few files. Changing VERSION, PATCHLEVEL or SUBLEVEL
| still does a major recompile, no way around that because of the number
| of places that test LINUX_VERSION_CODE and modules that need the kernel
| version string.

I'll let comments accumulate on this, but it seems to offer hope that
patching a few modules and changing the EXTRAVERSION so they go in their
own directory will not blow off eight minutes of time to recompile.
That's nice, assuming it works.

--
bill davidsen <[email protected]>
"If I were a diplomat, in the best case I'd go hungry. In the worst
case, people would die."
-- Robert Lipe

2001-10-08 17:56:20

by Bill Davidsen

[permalink] [raw]
Subject: Re: [patch] 2.4.11-pre4 remove spurious kernel recompiles

In article <[email protected]> [email protected] wrote:

| concentrating on correctness for kbuild 2.5. MEC mantra:
|
| Correctness comes first.
| Then maintainability.
| Then speed.

Sounds wrong to me... maintainability is done best at design time,
with modularity and by making things table driven where it makes sense.
Unless you hack at it until it works, then start with a new design to
implement what you learned, maintainability is better "built in not
added on" as the commercial says. Correctness is both a design and
implementation issue, of course.

If you design to be maintainable then correctness and speed are easier
to achieve because changes are easier and have fewer side effects.

As an example, the recent VM wars center on trying to see what works
badly and fixing it, rather than being a complete rewrite from scratch
of what has been learned and how to apply it. If the original design
had been made for easy changes, say by putting all the code in a
module, you could have a range of VM modules and a single source tree,
with options selected at boot time, perhaps.

I sense that there are many thoughts on dispatching as well, another
place where theories could be put into modules. Perhaps in 2.5?

--
bill davidsen <[email protected]>
"If I were a diplomat, in the best case I'd go hungry. In the worst
case, people would die."
-- Robert Lipe