When building an eCos configuration the primary target is a single
library, libtarget.a. In some cases it is
necessary to build some additional targets. For example architectural
HAL packages typically build a linker script and some start-up code.
Such additional targets can be specified by a make property. Any
option can have one or more make properties, although typically such
properties only occur in the body of a cdl_package command.
The make property takes a single argument, which resembles a
makefile rule: it consists of a target, a list of dependencies, and
one or more commands that should be executed. However the argument is
not a makefile fragment, and custom build steps may get executed in
build environments that do not involve make. For full details of
custom build steps see the Section called Custom Build Steps in Chapter 4.
Warning
The exact syntax and limitations of custom build steps have not yet
been finalized, and are subject to change in future versions of the
configuration tools.
The make property takes an optional priority argument indicating the
order in which build steps take place. This priority complements the
dependency list, and avoids problems with packages needing to know
details of custom build steps in other packages (which may change
between releases). The defined order is:
Priority 0
The header files exported by the current set of packages are copied
to the appropriate places in the
include subdirectory of the
install tree. Any unnecessary copies are avoided, to prevent rebuilds
of package and application source modules caused by header file dependencies.
Note: A possible future enhancement of the build system may result in the
build and install trees being updated automatically if there has been
a change to the ecos.ecc configuration savefile.
Priority 100
All files specified in compile properties will get built, producing
the corresponding object files. In addition any custom build steps
defined by make_object properties get executed, unless there is
a -priority= option.
Priority 200
The libraries now get built using the appropriate object files.
Priority 300
Any custom build steps specified by make properties now get
executed, unless the priority for a particular build step is changed
from its default.
For example, if a custom build step needs to take place before any of
the normal source files get compiled then it should be given a
priority somewhere between 0 and 100. If a custom build step involves
post-processing an object file prior to its incorporation into a
library then a priority between 100 and 200 should be used.
Example
cdl_package CYGPKG_HAL_MN10300_AM33 {
display "MN10300 AM33 variant"
parent CYGPKG_HAL_MN10300
implements CYGINT_HAL_MN10300_VARIANT
hardware
include_dir cyg/hal
define_header hal_mn10300_am33.h
description "
The MN10300 AM33 variant HAL package provides generic
support for this processor architecture. It is also
necessary to select a specific target platform HAL
package."
make {
<PREFIX>/lib/target.ld: <PACKAGE>/src/mn10300_am33.ld
$(CC) -E -P -Wp,-MD,target.tmp -DEXTRAS=1 -xc $(INCLUDE_PATH) $(CFLAGS) -o $@ $<
@echo $@ ": \\" > $(notdir $@).deps
@tail +2 target.tmp >> $(notdir $@).deps
@echo >> $(notdir $@).deps
@rm target.tmp
}
}
