CAVEAT: license change from BSD to Apache2 license!
Explanation:
The imported files come from CMSIS v5 project available on:
https://github.com/ARM-software/CMSIS_5/tree/develop
The files imported are located inside the CMSIS/Core/Include
project sub-directory.
The project does not provide any NOTICE file in its root directory nor
in the directory of the imported files.
The NOTICE file and its usage in the Apache 2 license was/is
so far the only issue mentioned in discussion of RTEMS developers/users
when considering inclusion of the code under Apache 2 license
into the RTEMS project.
Since the CMSIS v5 project is free from this legal hinder, we may freely
use it and update files to the latest version.
Technical: the patch replaces code from 2015 with the latest version
which brings quite a lot of bug fixes and most importantly opens
possibilities to support MCUs based on new ARM cores.
A speciality of the RTEMS build system was the make preinstall step. It
copied header files from arbitrary locations into the build tree. The
header files were included via the -Bsome/build/tree/path GCC command
line option.
This has at least seven problems:
* The make preinstall step itself needs time and disk space.
* Errors in header files show up in the build tree copy. This makes it
hard for editors to open the right file to fix the error.
* There is no clear relationship between source and build tree header
files. This makes an audit of the build process difficult.
* The visibility of all header files in the build tree makes it
difficult to enforce API barriers. For example it is discouraged to
use BSP-specifics in the cpukit.
* An introduction of a new build system is difficult.
* Include paths specified by the -B option are system headers. This
may suppress warnings.
* The parallel build had sporadic failures on some hosts.
This patch removes the make preinstall step. All installed header
files are moved to dedicated include directories in the source tree.
Let @RTEMS_CPU@ be the target architecture, e.g. arm, powerpc, sparc,
etc. Let @RTEMS_BSP_FAMILIY@ be a BSP family base directory, e.g.
erc32, imx, qoriq, etc.
The new cpukit include directories are:
* cpukit/include
* cpukit/score/cpu/@RTEMS_CPU@/include
* cpukit/libnetworking
The new BSP include directories are:
* bsps/include
* bsps/@RTEMS_CPU@/include
* bsps/@RTEMS_CPU@/@RTEMS_BSP_FAMILIY@/include
There are build tree include directories for generated files.
The include directory order favours the most general header file, e.g.
it is not possible to override general header files via the include path
order.
The "bootstrap -p" option was removed. The new "bootstrap -H" option
should be used to regenerate the "headers.am" files.
Update #3254.
