[PATCH] kbuild doc: move smart-config.txt to Doc/kbuild/

Randy Dunlap
2008-03-03T23:01:16Z

From: Randy Dunlap <randy.dunlap@oracle.com>

I'm trying to clean up some of the Documentation diretory.
What do you think about this one?

Move smart-config.txt to Documentation/kbuild/ since it is
build/config-related.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
---
Documentation/kbuild/smart-config.txt | 98 ++++++++++++++++++++++++
Documentation/smart-config.txt | 98 ------------------------
2 files changed, 98 insertions(+), 98 deletions(-)

--- /dev/null
+++ linux-2.6.25-rc3-git4/Documentation/kbuild/smart-config.txt
@@ -0,0 +1,98 @@
+Smart CONFIG_* Dependencies
+1 August 1999
+
+Michael Chastain <mec@shout.net>
+Werner Almesberger <almesber@lrc.di.epfl.ch>
+Martin von Loewis <martin@mira.isdn.cs.tu-berlin.de>
+
+Here is the problem:
+
+ Suppose that drivers/net/foo.c has the following lines:
+
+ #include <linux/config.h>
+
+ ...
+
+ #ifdef CONFIG_FOO_AUTOFROB
+ /* Code for auto-frobbing */
+ #else
+ /* Manual frobbing only */
+ #endif
+
+ ...
+
+ #ifdef CONFIG_FOO_MODEL_TWO
+ /* Code for model two */
+ #endif
+
+ Now suppose the user (the person building kernels) reconfigures the
+ kernel to change some unrelated setting. This will regenerate the
+ file include/linux/autoconf.h, which will cause include/linux/config.h
+ to be out of date, which will cause drivers/net/foo.c to be recompiled.
+
+ Most kernel sources, perhaps 80% of them, have at least one CONFIG_*
+ dependency somewhere. So changing _any_ CONFIG_* setting requires
+ almost _all_ of the kernel to be recompiled.
+
+Here is the solution:
+
+ We've made the dependency generator, mkdep.c, smarter. Instead of
+ generating this dependency:
+
+ drivers/net/foo.c: include/linux/config.h
+
+ It now generates these dependencies:
+
+ drivers/net/foo.c: \
+ include/config/foo/autofrob.h \
+ include/config/foo/model/two.h
+
+ So drivers/net/foo.c depends only on the CONFIG_* lines that
+ it actually uses.
+
+ A new program, split-include.c, runs at the beginning of
+ compilation (make bzImage or make zImage). split-include reads
+ include/linux/autoconf.h and updates the include/config/ tree,
+ writing one file per option. It updates only the files for options
+ that have changed.
+
+Flag Dependencies
+
+ Martin Von Loewis contributed another feature to this patch:
+ 'flag dependencies'. The idea is that a .o file depends on
+ the compilation flags used to build it. The file foo.o has
+ its flags stored in .flags.foo.o.
+
+ Suppose the user changes the foo driver from resident to modular.
+ 'make' will notice that the current foo.o was not compiled with
+ -DMODULE and will recompile foo.c.
+
+ All .o files made from C source have flag dependencies. So do .o
+ files made with ld, and .a files made with ar. However, .o files
+ made from assembly source do not have flag dependencies (nobody
+ needs this yet, but it would be good to fix).
+
+Per-source-file Flags
+
+ Flag dependencies also work with per-source-file flags.
+ You can specify compilation flags for individual source files
+ like this:
+
+ CFLAGS_foo.o = -DSPECIAL_FOO_DEFINE
+
+ This helps clean up drivers/net/Makefile, drivers/scsi/Makefile,
+ and several other Makefiles.
+
+Credit
+
+ Werner Almesberger had the original idea and wrote the first
+ version of this patch.
+
+ Michael Chastain picked it up and continued development. He is
+ now the principal author and maintainer. Please report any bugs
+ to him.
+
+ Martin von Loewis wrote flag dependencies, with some modifications
+ by Michael Chastain.
+
+ Thanks to all of the beta testers.
--- linux-2.6.25-rc3-git4.orig/Documentation/smart-config.txt
+++ /dev/null
@@ -1,98 +0,0 @@
-Smart CONFIG_* Dependencies
-1 August 1999
-
-Michael Chastain <mec@shout.net>
-Werner Almesberger <almesber@lrc.di.epfl.ch>
-Martin von Loewis <martin@mira.isdn.cs.tu-berlin.de>
-
-Here is the problem:
-
- Suppose that drivers/net/foo.c has the following lines:
-
- #include <linux/config.h>
-
- ...
-
- #ifdef CONFIG_FOO_AUTOFROB
- /* Code for auto-frobbing */
- #else
- /* Manual frobbing only */
- #endif
-
- ...
-
- #ifdef CONFIG_FOO_MODEL_TWO
- /* Code for model two */
- #endif
-
- Now suppose the user (the person building kernels) reconfigures the
- kernel to change some unrelated setting. This will regenerate the
- file include/linux/autoconf.h, which will cause include/linux/config.h
- to be out of date, which will cause drivers/net/foo.c to be recompiled.
-
- Most kernel sources, perhaps 80% of them, have at least one CONFIG_*
- dependency somewhere. So changing _any_ CONFIG_* setting requires
- almost _all_ of the kernel to be recompiled.
-
-Here is the solution:
-
- We've made the dependency generator, mkdep.c, smarter. Instead of
- generating this dependency:
-
- drivers/net/foo.c: include/linux/config.h
-
- It now generates these dependencies:
-
- drivers/net/foo.c: \
- include/config/foo/autofrob.h \
- include/config/foo/model/two.h
-
- So drivers/net/foo.c depends only on the CONFIG_* lines that
- it actually uses.
-
- A new program, split-include.c, runs at the beginning of
- compilation (make bzImage or make zImage). split-include reads
- include/linux/autoconf.h and updates the include/config/ tree,
- writing one file per option. It updates only the files for options
- that have changed.
-
-Flag Dependencies
-
- Martin Von Loewis contributed another feature to this patch:
- 'flag dependencies'. The idea is that a .o file depends on
- the compilation flags used to build it. The file foo.o has
- its flags stored in .flags.foo.o.
-
- Suppose the user changes the foo driver from resident to modular.
- 'make' will notice that the current foo.o was not compiled with
- -DMODULE and will recompile foo.c.
-
- All .o files made from C source have flag dependencies. So do .o
- files made with ld, and .a files made with ar. However, .o files
- made from assembly source do not have flag dependencies (nobody
- needs this yet, but it would be good to fix).
-
-Per-source-file Flags
-
- Flag dependencies also work with per-source-file flags.
- You can specify compilation flags for individual source files
- like this:
-
- CFLAGS_foo.o = -DSPECIAL_FOO_DEFINE
-
- This helps clean up drivers/net/Makefile, drivers/scsi/Makefile,
- and several other Makefiles.
-
-Credit
-
- Werner Almesberger had the original idea and wrote the first
- version of this patch.
-
- Michael Chastain picked it up and continued development. He is
- now the principal author and maintainer. Please report any bugs
- to him.
-
- Martin von Loewis wrote flag dependencies, with some modifications
- by Michael Chastain.
-
- Thanks to all of the beta testers.