$NetBSD: README,v 1.7 2011/04/17 01:29:06 mrg Exp $ Building multi- ABI libraries for NetBSD platforms. src/compat has a framework to (re)build the libraries shipped with NetBSD for a different ABI than the default for that platform. This allows 32-bit libraries for the amd64 and sparc64 ports, and enables the mips64 port to support all three of old-style 32-bit ("o32"), the new 32-bit (default, "n32", 64-bit CPU required) or the 64-bit ABI. The basic premise is to re-set $MAKEOBJDIR to fresh subdirectory underneath src/compat and rebuild the libraries with a different set of options. Each platform wanting support should create their port subdirectory directly in src/compat, and then one subdirectory in here for each ABI required. e.g., src/compat/amd64/i386 is where we build the 32-bit compat libraries for the amd64 port. In each of these subdirs, a small Makefile and makefile fragment should exist. The Makefile should set BSD_MK_COMPAT_FILE to equal the fragment, and then include "../../compatsubdir.mk" Eg, amd64/i386/Makefile has: BSD_MK_COMPAT_FILE=${.CURDIR}/bsd.i386.mk .include "../../compatsubdir.mk" In the makefile fragment any changes to ABI flags are passed here and the MLIBDIR variable must be set to the subdirectory in /usr/lib where libraries for the ABI will be installed. There are a couple of helper Makefiles around. amd64/i386/bsd.i386.mk looks like: LD+= -m elf_i386 MLIBDIR= i386 LIBC_MACHINE_ARCH= ${MLIBDIR} COMMON_MACHINE_ARCH= ${MLIBDIR} KVM_MACHINE_ARCH= ${MLIBDIR} PTHREAD_MACHINE_ARCH= ${MLIBDIR} BFD_MACHINE_ARCH= ${MLIBDIR} CSU_MACHINE_ARCH= ${MLIBDIR} CRYPTO_MACHINE_CPU= ${MLIBDIR} LDELFSO_MACHINE_CPU= ${MLIBDIR} .include "${NETBSDSRCDIR}/compat/m32.mk" and the referenced m32.mk looks like: COPTS+= -m32 CPUFLAGS+= -m32 LDADD+= -m32 LDFLAGS+= -m32 MKDEPFLAGS+= -m32 .include "Makefile.compat" compatsubdir.mk holds the list of subdirectories (the libraries and ld.elf_so) to build with this ABI. archdirs.mk holds the list of subdirectories for each port. Makefile.compat has the basic framework to force the right paths for library and ld.elf_so linkage. It contains a hack to create subdirs in the build that should be fixed. dirshack/Makefile is a hack to get objdirs created timely, and should be fixed in a better way. mrg@eterna.com.au december 2009