Add support for a project directory

Many buildroot users prefer to keep their project's customizations
separate from buildroot itself. This makes it easier to go to a new buildroot version, and to identify which parts are project- specific. Although it was already possible to keep the project's customization separate, this patch set simplifies it.

It introduces a new config option, BR2_PROJECT_DIR (patch 1).
This symbol is used to set defaults for many other config options (patches 2-7). The buildroot config itself can also be stored in the project directory by setting a default BR2_DEFCONFIG (patch 8).

Patch 9 does a 'make defconfig' and 'make world' in a single run
when a project directory is available.

Patch 10 makes it possible to update all config files (buildroot,
linux, busybox, ...) in a single shot.

Patch 11 adds a 'make projectdir' target to initialize a project
directory. It also creates a Makefile in the project directory:
it downloads buildroot itself, so the project directory is self-sufficient.

Patch 12 adds the thing that everybody has to put in their
post-build script as a configuration option: a rootfs overlay. This patch could also be applied independent of the series (except for the one line that sets a default based on PROJECT_DIR).

Patch 13, finally, adds the PROJECT_DIR concept to the manual.

What is still missing is a way to add custom packages and custom
patches in the project directory. Either can already be done with the BR2_PACKAGE_OVERRIDE_FILE, but I'm considering specific additions:

- For custom packages, including $(PROJECT_DIR)/package/*/*.mk and automatically setting these packages to 'y'. I don't think it's useful to include custom packages in the menuconfig - you just want them to be always enabled.

- For custom patches, add $(PROJECT_DIR)/patches/<pkg>/<pkg>-*.patch to the list of patches that generic-package looks for. The custom patches would come in addition to and after the buildroot patches.

Comments on these last two ideas are welcome.

Two weeks from now (Oct. 28) I'm giving a presentation about buildroot
at T-Dose in Eindhoven. I'll use the project directory concept in that presentation. So if there's any major feedback I'd like to hear it before that time :-)

Regards,
Arnout

---

Arnout Vandecappelle (Essensium/Mind) (13):
Add BR2_PROJECT_DIR config option
Set default BR2_PACKAGE_OVERRIDE_FILE based on BR2_PROJECT_DIR
linux: get default paths from BR2_PROJECT_DIR
busybox: get default paths from BR2_PROJECT_DIR target/generic: get default paths from BR2_PROJECT_DIR
toolchain-crosstool-ng: get default paths from BR2_PROJECT_DIR
uClibc: get default paths from BR2_PROJECT_DIR
Store BR2_DEFCONFIG in .config, and use it to update the original input Skip menuconfig if BR2_DEFCONFIG or BR2_PROJECT_DIR is given. Add update-all-config target
Add target to create a project directory
target/generic: add filesystem overlay option
Document BR2_PROJECT_DIR in the manual

 Config.in                                        |   27 +++++++
 Makefile                                         |   86 +++++++++++++++++++--
 Makefile.project.tmpl                            |   40 ++++++++++
 docs/manual/customize-project.txt                |   37 +++++++++
 docs/manual/customize-rootfs.txt                 |   21 ++---
 docs/manual/customize.txt                        |    2 
 fs/common.mk                                     |    7 +-
 linux/Config.in                                  |    2 
 linux/linux.mk                                   |    2 
 package/busybox/Config.in                        |    1 
 package/busybox/busybox-1.20.x.config            |   26 +++---
 package/busybox/busybox.mk                       |    4 +
 target/generic/Config.in                         |   16 ++++
 toolchain/toolchain-crosstool-ng/Config.in       |    1 
 toolchain/toolchain-crosstool-ng/crosstool-ng.mk |    7 ++
 toolchain/uClibc/Config.in                       |    1 
 toolchain/uClibc/uClibc-0.9.33.config            |   91 +++++++++-------------
 toolchain/uClibc/uclibc.mk                       |    4 +
 18 files changed, 286 insertions(+), 89 deletions(-)
 create mode 100644 Makefile.project.tmpl
 create mode 100644 docs/manual/customize-project.txt

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