Comtrol eCos - Manual (Page 348)

Chapter 11. Porting Guide
CDL Requirements
The CDL needed for any particular architecture HAL depends to a large extent on the needs of that architecture.
This includes issues such as support for different variants, use of FPUs, MMUs and caches. The exact split between
the architecture, variant and platform HALs for various features is also somewhat fluid.
To give a rough idea about how the CDL for an architecture is structured, we will take as an example the I386
CDL.
This first section introduces the CDL package and placed it under the main HAL package. Include files from
this package will be put in the
include/cyg/hal directory, and definitions from this file will be placed in in-
clude/pkgconf/hal_i386.h . The compile line specifies the files in the src directory that are to be compiled
as part of this package.
cdl_package CYGPKG_HAL_I386 {
display "i386 architecture"
parent CYGPKG_HAL
hardware
include_dir cyg/hal
define_header hal_i386.h
description "
The i386 architecture HAL package provides generic
support for this processor architecture. It is also
necessary to select a specific target platform HAL
package."
compile hal_misc.c context.S i386_stub.c hal_syscall.c
Next we need to generate some files using non-standard make rules. The first is vectors.S , which is not put into
the library, but linked explicitly with all applications. The second is the generation of the target.ld file from
i386.ld and the startup-selected .ldi file. Both of these are essentially boilerplate code that can be copied and
edited.
make {
< PREFIX > /lib/vectors.o : < PACKAGE > /src/vectors.S
$(CC) -Wp,-MD,vectors.tmp $(INCLUDE_PATH) $(CFLAGS) -c -o $@ $ <
@echo $@ ": \\" > $(notdir $@).deps
@tail +2 vectors.tmp >> $(notdir $@).deps
@echo >> $(notdir $@).deps
@rm vectors.tmp
}
make {
< PREFIX > /lib/target.ld: < PACKAGE > /src/i386.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
}
244