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Annotation of src/compat/README, Revision 1.8

1.8     ! wiz         1: $NetBSD: README,v 1.7 2011/04/17 01:29:06 mrg Exp $
1.1       mrg         2:
                      3:
1.8     ! wiz         4: Building multi-ABI libraries for NetBSD platforms.
1.1       mrg         5:
                      6:
1.4       mrg         7: src/compat has a framework to (re)build the libraries shipped with
                      8: NetBSD for a different ABI than the default for that platform.  This
1.5       snj         9: allows 32-bit libraries for the amd64 and sparc64 ports, and enables
1.4       mrg        10: the mips64 port to support all three of old-style 32-bit ("o32"), the
                     11: new 32-bit (default, "n32", 64-bit CPU required) or the 64-bit ABI.
1.1       mrg        12:
                     13:
1.7       mrg        14: The basic premise is to re-set $MAKEOBJDIR to fresh subdirectory
1.4       mrg        15: underneath src/compat and rebuild the libraries with a different set
                     16: of options.  Each platform wanting support should create their port
                     17: subdirectory directly in src/compat, and then one subdirectory in here
1.8     ! wiz        18: for each ABI required, e.g., src/compat/amd64/i386 is where we build
1.5       snj        19: the 32-bit compat libraries for the amd64 port.  In each of these
1.8     ! wiz        20: subdirectories, a small Makefile and makefile fragment should exist.  The
1.4       mrg        21: Makefile should set BSD_MK_COMPAT_FILE to equal the fragment, and then
1.8     ! wiz        22: include "../../compatsubdir.mk".  E.g., amd64/i386/Makefile has:
1.1       mrg        23:
1.4       mrg        24:        BSD_MK_COMPAT_FILE=${.CURDIR}/bsd.i386.mk
1.1       mrg        25:
1.6       mrg        26:        .include "../../compatsubdir.mk"
1.1       mrg        27:
1.4       mrg        28: In the makefile fragment any changes to ABI flags are passed here
                     29: and the MLIBDIR variable must be set to the subdirectory in /usr/lib
                     30: where libraries for the ABI will be installed.  There are a couple of
1.5       snj        31: helper Makefiles around.  amd64/i386/bsd.i386.mk looks like:
1.1       mrg        32:
1.4       mrg        33:        LD+=                    -m elf_i386
                     34:        MLIBDIR=                i386
                     35:        LIBC_MACHINE_ARCH=      ${MLIBDIR}
                     36:        COMMON_MACHINE_ARCH=    ${MLIBDIR}
                     37:        KVM_MACHINE_ARCH=       ${MLIBDIR}
                     38:        PTHREAD_MACHINE_ARCH=   ${MLIBDIR}
                     39:        BFD_MACHINE_ARCH=       ${MLIBDIR}
                     40:        CSU_MACHINE_ARCH=       ${MLIBDIR}
                     41:        CRYPTO_MACHINE_CPU=     ${MLIBDIR}
                     42:        LDELFSO_MACHINE_CPU=    ${MLIBDIR}
1.1       mrg        43:
1.6       mrg        44:        .include "${NETBSDSRCDIR}/compat/m32.mk"
1.4       mrg        45:
1.6       mrg        46: and the referenced m32.mk looks like:
1.4       mrg        47:
                     48:        COPTS+=                 -m32
                     49:        CPUFLAGS+=              -m32
                     50:        LDADD+=                 -m32
                     51:        LDFLAGS+=               -m32
                     52:        MKDEPFLAGS+=            -m32
                     53:
                     54:        .include "Makefile.compat"
                     55:
                     56:
1.6       mrg        57: compatsubdir.mk holds the list of subdirectories (the libraries and
1.4       mrg        58: ld.elf_so) to build with this ABI.
                     59:
1.6       mrg        60: archdirs.mk holds the list of subdirectories for each port.
1.4       mrg        61:
                     62: Makefile.compat has the basic framework to force the right paths for
1.8     ! wiz        63: library and ld.elf_so linkage.  It contains a hack to create subdirectories
1.4       mrg        64: in the build that should be fixed.
                     65:
                     66: dirshack/Makefile is a hack to get objdirs created timely, and should
                     67: be fixed in a better way.
                     68:
                     69:
                     70:
                     71: mrg@eterna.com.au
                     72: december 2009