When the configuration tools generate a build tree, one of the steps
is to output each package's configuration data to a header file. For
example the kernel's configuration data gets output to
pkgconf/kernel.h. This allows
each package's source code to #include the
appropriate header file and adapt to the choices made by the user.
By default the configuration tools will synthesize a file name from
the package name. This involves removing any prefix such as
CYGPKG_, up to and including the first underscore,
and then converting the remainder of the name to lower case. In some
cases it may be desirable to use a different header file, for example
an existing package may have been ported to eCos and the source code
may already #include a particular file for
configuration data. In such cases a define_header property can be
used to specify an alternative filename.
The define_header property can only be used in the body of a
cdl_package command. It applies to a package as a whole and cannot
be used at a finer grain. The name specified in a define_header
property will always be interpreted as relative to the
include/pkgconf sub-directory
of the install tree.
Note: For hardware-specific packages such as device drivers and HAL
packages, the current scheme of generating a configuration header file
name based on the package name may be abandoned. Instead all hardware
packages would send their configuration data to a single header file,
pkgconf/hardware.h. This would
make it easier for code to obtain details of the current hardware, but
obviously there are compatibility issues. For now it is recommended
that all hardware packages specify their configuration header file
explicitly.
