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Thomas Petazzoni f7add51c39 qemu: add host/target Linux version check
Raise an error if the host is using an older kernel than the target.
Since qemu-user passes emulated system calls to the host kernel,
this prevents usage of qemu-user in situations where those system
calls will fail.

This is based on an original patch from Frank Hunleth
<fhunleth@troodon-software.com>, but completely rewritten in a
different way:

 * Instead of using shell based testing, we use pure make tests, which
   allows to detect the problem not when host-qemu starts to build,
   but at the very beginning of the entire Buildroot build.

 * Instead of looking at $(STAGING_DIR)/usr/include/linux/version.h
   (which requires having a dependency on the 'toolchain' package,
   which is a bit unusual for a host package), we use the
   BR2_TOOLCHAIN_HEADERS_AT_LEAST Config.in option which tells us the
   version of the kernel headers used in the toolchain.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Frank Hunleth <fhunleth@troodon-software.com>
2014-12-23 12:09:29 +01:00
arch Turn the static lib option into a choice with more options 2014-12-12 00:09:02 +01:00
board configs/qemu: update infos for latest qemu version 2014-12-16 00:46:20 +01:00
boot boot/uboot: bump to version 2014.10 2014-12-21 23:24:09 +01:00
configs configs/qemu: update to the latest kernel/headers versions 2014-12-09 14:30:37 +01:00
docs manual: remove the extra whitespaces 2014-12-20 15:55:54 +01:00
fs package: indentation cleanup 2014-12-10 21:53:30 +01:00
linux linux: bump default to version 3.18.1 2014-12-16 23:47:24 +01:00
package qemu: add host/target Linux version check 2014-12-23 12:09:29 +01:00
support support/libtool: add patch for newer versions 2014-12-21 13:21:56 +01:00
system Rename BR2_PREFER_STATIC_LIB to BR2_STATIC_LIBS 2014-12-11 22:48:13 +01:00
toolchain toolchain: get rid of -pipe from optimisations 2014-12-21 22:04:59 +01:00
.defconfig
.gitignore
CHANGES Update for 2014.11 2014-12-01 10:19:00 +01:00
Config.in Build shared libraries only as the default 2014-12-12 00:09:41 +01:00
Config.in.legacy legacy: update the BR2_PREFER_STATIC_LIB option 2014-12-14 17:50:25 +01:00
COPYING
Makefile Merge branch 'next' 2014-12-01 11:16:42 +01:00
Makefile.legacy Makefile.legacy: fix recursive invocation with BUILDROOT_DL_DIR and _CONFIG 2014-02-11 08:14:57 +01:00
README docs: Move README file to root 2014-03-03 21:28:39 +01:00

To build and use the buildroot stuff, do the following:

1) run 'make menuconfig'
2) select the packages you wish to compile
3) run 'make'
4) wait while it compiles
5) Use your shiny new root filesystem. Depending on which sort of
    root filesystem you selected, you may want to loop mount it,
    chroot into it, nfs mount it on your target device, burn it
    to flash, or whatever is appropriate for your target system.

You do not need to be root to build or run buildroot.  Have fun!

Offline build:
==============

In order to do an offline-build (not connected to the net), fetch all
selected source by issuing a
$ make source

before you disconnect.
If your build-host is never connected, then you have to copy buildroot
and your toplevel .config to a machine that has an internet-connection
and issue "make source" there, then copy the content of your dl/ dir to
the build-host.

Building out-of-tree:
=====================

Buildroot supports building out of tree with a syntax similar
to the Linux kernel. To use it, add O=<directory> to the
make command line, E.G.:

$ make O=/tmp/build

And all the output files (including .config) will be located under /tmp/build.

More finegrained configuration:
===============================

You can specify a config-file for uClibc:
$ make UCLIBC_CONFIG_FILE=/my/uClibc.config

And you can specify a config-file for busybox:
$ make BUSYBOX_CONFIG_FILE=/my/busybox.config

To use a non-standard host-compiler (if you do not have 'gcc'),
make sure that the compiler is in your PATH and that the library paths are
setup properly, if your compiler is built dynamically:
$ make HOSTCC=gcc-4.3.orig HOSTCXX=gcc-4.3-mine

Depending on your configuration, there are some targets you can use to
use menuconfig of certain packages. This includes:
$ make HOSTCC=gcc-4.3 linux-menuconfig
$ make HOSTCC=gcc-4.3 uclibc-menuconfig
$ make HOSTCC=gcc-4.3 busybox-menuconfig

Please feed suggestions, bug reports, insults, and bribes back to the
buildroot mailing list: buildroot@buildroot.org