linux-toradex.git/Documentation/kbuild, branch v4.10

Kconfig: Introduce the "imply" keyword

2016-11-16T08:26:33+00:00

The "imply" keyword is a weak version of "select" where the target
config symbol can still be turned off, avoiding those pitfalls that come
with the "select" keyword.

This is useful e.g. with multiple drivers that want to indicate their
ability to hook into a secondary subsystem while allowing the user to
configure that subsystem out without also having to unset these drivers.

Currently, the same effect can almost be achieved with:

config DRIVER_A
	tristate

config DRIVER_B
	tristate

config DRIVER_C
	tristate

config DRIVER_D
	tristate

[...]

config SUBSYSTEM_X
	tristate
	default DRIVER_A || DRIVER_B || DRIVER_C || DRIVER_D || [...]

This is unwieldy to maintain especially with a large number of drivers.
Furthermore, there is no easy way to restrict the choice for SUBSYSTEM_X
to y or n, excluding m, when some drivers are built-in. The "select"
keyword allows for excluding m, but it excludes n as well. Hence
this "imply" keyword.  The above becomes:

config DRIVER_A
	tristate
	imply SUBSYSTEM_X

config DRIVER_B
	tristate
	imply SUBSYSTEM_X

[...]

config SUBSYSTEM_X
	tristate

This is much cleaner, and way more flexible than "select". SUBSYSTEM_X
can still be configured out, and it can be set as a module when none of
the drivers are configured in or all of them are modular.

Signed-off-by: Nicolas Pitre 
Acked-by: Richard Cochran 
Acked-by: Thomas Gleixner 
Acked-by: John Stultz 
Reviewed-by: Josh Triplett 
Cc: Paul Bolle 
Cc: linux-kbuild@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Michal Marek 
Cc: Edward Cree 
Link: http://lkml.kernel.org/r/1478841010-28605-2-git-send-email-nicolas.pitre@linaro.org
Signed-off-by: Thomas Gleixner

Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild

2016-10-14T21:26:58+00:00

Pull kbuild updates from Michal Marek:

 - EXPORT_SYMBOL for asm source by Al Viro.

   This does bring a regression, because genksyms no longer generates
   checksums for these symbols (CONFIG_MODVERSIONS). Nick Piggin is
   working on a patch to fix this.

   Plus, we are talking about functions like strcpy(), which rarely
   change prototypes.

 - Fixes for PPC fallout of the above by Stephen Rothwell and Nick
   Piggin

 - fixdep speedup by Alexey Dobriyan.

 - preparatory work by Nick Piggin to allow architectures to build with
   -ffunction-sections, -fdata-sections and --gc-sections

 - CONFIG_THIN_ARCHIVES support by Stephen Rothwell

 - fix for filenames with colons in the initramfs source by me.

* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (22 commits)
  initramfs: Escape colons in depfile
  ppc: there is no clear_pages to export
  powerpc/64: whitelist unresolved modversions CRCs
  kbuild: -ffunction-sections fix for archs with conflicting sections
  kbuild: add arch specific post-link Makefile
  kbuild: allow archs to select link dead code/data elimination
  kbuild: allow architectures to use thin archives instead of ld -r
  kbuild: Regenerate genksyms lexer
  kbuild: genksyms fix for typeof handling
  fixdep: faster CONFIG_ search
  ia64: move exports to definitions
  sparc32: debride memcpy.S a bit
  [sparc] unify 32bit and 64bit string.h
  sparc: move exports to definitions
  ppc: move exports to definitions
  arm: move exports to definitions
  s390: move exports to definitions
  m68k: move exports to definitions
  alpha: move exports to actual definitions
  x86: move exports to actual definitions
  ...

kbuild: add arch specific post-link Makefile

2016-09-09T08:47:00+00:00

Allow architectures to create arch/xxx/Makefile.postlink with targets
for vmlinux, modules.ko, and clean, which will be invoked after final
linking of vmlinux and modules.

powerpc will use this to check vmlinux linker relocations for sanity,
and may use it to fix up alternate instruction patch branch addresses.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michal Marek

kconfig-language: improve menuconfig usage description

2016-08-18T21:23:31+00:00

Improper menuconfig usage leads to empty menu entries.
zconfdump() is able to reveal some real-life examples:
- menuconfig VFIO_NOIOMMU
- menuconfig RESET_CONTROLLER
- menuconfig SND_ARM

To avoid future occurrences of those, improve the menuconfig syntax
description.

Signed-off-by: Eugeniu Rosca 
Signed-off-by: Jonathan Corbet

kbuild, x86: Track generated headers with generated-y

2016-07-07T13:58:44+00:00

Track generated header files which aren't already in genhdr-y, alongside
generic-y wrappers in the */include/generated/[uapi/]asm/ directories.
Currently only x86 generates extra headers in these directories, for the
purposes of enumerating system calls for different ABIs, and xen
hypercalls.

This will allow the asm-generic wrapper handling code to remove stale
wrappers when files are removed from generic-y, without also removing
these headers which are generated separately.

Reported-by: kbuild test robot 
Signed-off-by: James Hogan 
Acked-by: Arnd Bergmann 
Cc: Jonathan Corbet 
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: Michal Marek 
Link: http://lkml.kernel.org/r/1466808144-23209-2-git-send-email-james.hogan@imgtec.com
Signed-off-by: Thomas Gleixner

kconfig-language: elaborate on the type of a choice

2016-05-10T15:30:14+00:00

The type of a choice can be specified explicitely or it will be
set according to members of the choice group, see menu.c:menu_finalize().

Signed-off-by: Dirk Gouders 
Signed-off-by: Michal Marek

kconfig-language: fix comment on dependency-generated menu structures.

2016-05-10T15:30:09+00:00

In the given example, the comment becomes visible when it's dependency
is set to 'n', but the text asserts the opposite.

Signed-off-by: Dirk Gouders 
Signed-off-by: Michal Marek

kbuild: document recursive dependency limitation / resolution

2015-10-08T13:36:16+00:00

Recursive dependency issues with kconfig are unavoidable due to
some limitations with kconfig, since these issues are recurring
provide a hint to the user how they can resolve these dependency
issues and also document why such limitation exists.

While at it also document a bit of future prospects of ways to
enhance Kconfig, including providing formal semantics and evaluation
of use of a SAT solver. If you're interested in this work or prospects
of it check out the kconfig-sat project wiki [0] and mailing list [1].

[0] http://kernelnewbies.org/KernelProjects/kconfig-sat
[1] https://groups.google.com/d/forum/kconfig-sat

Cc: Geert Uytterhoeven 
Cc: James Bottomley 
Cc: Josh Triplett 
Cc: Paul Bolle 
Cc: Herbert Xu 
Cc: Takashi Iwai 
Cc: "Yann E. MORIN" 
Cc: Jonathan Corbet 
Cc: Mate Soos 
Signed-off-by: Luis R. Rodriguez 
Signed-off-by: Michal Marek

modsign: Allow password to be specified for signing key

2015-08-07T15:26:14+00:00

We don't want this in the Kconfig since it might then get exposed in
/proc/config.gz. So make it a parameter to Kbuild instead. This also
means we don't have to jump through hoops to strip quotes from it, as
we would if it was a config option.

Signed-off-by: David Woodhouse 
Signed-off-by: David Howells 
Reviewed-by: Mimi Zohar

kbuild: Allow arch Makefiles to override {cpp,ld,c}flags

2015-07-06T05:39:00+00:00

Since commit a1c48bb1 (Makefile: Fix unrecognized cross-compiler command
line options), the arch Makefile is included earlier by the main
Makefile, preventing the arc architecture to set its -O3 compiler
option. Since there might be more use cases for an arch Makefile to
fine-tune the options, add support for ARCH_CPPFLAGS, ARCH_AFLAGS and
ARCH_CFLAGS variables that are appended to the respective kbuild
variables. The user still has the final say via the KCPPFLAGS, KAFLAGS
and KCFLAGS variables.

Reported-by: Vineet Gupta 
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Michal Marek