cross compiling ARM ramdisk kernel on x86 host fails

[Patrick Oeschger-2]

i tied to cross compile a ARM ramdisk kernel on x86 and am somewhat
stuck
what i did:

rm -rf /usr/cross/armish /usr/obj/*
cd /usr/src/distrib/crunch
make
make install
cd /usr/src
make obj
make cross-tools TARGET=armish
make cross-distrib TARGET=armish
export DESTDIR=/usr/cross/armish
export AS=/usr/cross/armish/usr/bin/as
export CC=/usr/cross/armish/usr/bin/gcc
export GCC=/usr/cross/armish/usr/bin/gcc
export CPP=/usr/cross/armish/usr/bin/cpp
export LD=/usr/cross/armish/usr/bin/ld
export STRIP=/usr/cross/armish/usr/bin/strip
cd /usr/src/distrib/special
make TARGET=armish
cd /usr/src/distrib/armish
make TARGET=armish

everything works until executing the last command

/usr/src/distrib/armish/ramdisk/obj/rdsetroot bsd.rd < mr.fs
bsd.rd: no rd_root_image symbols?
*** Error code 1
Stop in /usr/src/distrib/armish/ramdisk (line 41 of /usr/src/distrib/armish/ramdisk/Makefile).
*** Error code 1
Stop in /usr/src/distrib/armish (line 48 of /usr/share/mk/bsd.subdir.mk).

this seems to be related to the fact that rdsetroot will check for the machine arch to the the same as the host arch which is not the case - we are cross compiling for armish
uncommenting the 'exit(1);' on line 217 of elfrdsetroot.c will help but gives another error:

/usr/src/distrib/armish/ramdisk/obj/rdsetroot bsd.rd < mr.fs
bsd.rd: no rd_root_image symbols?
segment 0 rd_root_size_off = 0xffe00000
rd_root_image_off = 0xffe00000
bsd.rd: no rd_root_image symbols?
segment 1 rd_root_size_off = 0x3fdfff3c
root_off v c02000c4 p 2000c4, diff c0000000 altered 7fdfff3c
rd_root_image_off = 0x3fdfff3c
bsd.rd: no rd_root_image symbols?
segment 2 rd_root_size_off = 0x3fc18000
root_off v c03e8000 p 3e8000, diff c0000000 altered 7fc18000
rd_root_image_off = 0x3fc18000
bsd.rd: no rd_root_image symbols?
segment 3 rd_root_size_off = 0x3f98de9c
rd_root_image_off = 0x3f98de9c
bsd.rd: can't locate space for rd_root_image!
*** Error code 1
Stop in /usr/src/distrib/armish/ramdisk (line 41 of /usr/src/distrib/armish/ramdisk/Makefile).
*** Error code 1
Stop in /usr/src/distrib/armish (line 48 of /usr/share/mk/bsd.subdir.mk).

- any idea/hints on how to cross compile a arm release or ramdisk
  kernel on a x86 host?
- how is the openbsd release being compiled...
  also cross on a x86 host or native on a arm host?

many thanks
/pat

[Dale Rahn]

On Thu, Apr 09, 2009 at 10:05:03PM +0200, Patrick Oeschger wrote:
> i tied to cross compile a ARM ramdisk kernel on x86 and am somewhat
> stuck
> what i did:
>
[snip]
>
> - any idea/hints on how to cross compile a arm release or ramdisk
>   kernel on a x86 host?
> - how is the openbsd release being compiled...
>   also cross on a x86 host or native on a arm host?

First, cross build is not officially supported by OpenBSD, all releases
are built natively. However some support for cross builds exist in the
tree primarily for intial bringup effort for a platform.

>
> many thanks
> /pat
>

I have a diff that I have been sitting on for some time that works around this.
It adds an ifdef to the libc code and then compiles it into the binary
so the arch check is disabled.

I also have another useful 'environment' script that I use, below.

Index: distrib/armish/ramdisk/Makefile
===================================================================
RCS file: /cvs/src/distrib/armish/ramdisk/Makefile,v
retrieving revision 1.6
diff -u -u -r1.6 Makefile
--- distrib/armish/ramdisk/Makefile 2 Dec 2008 03:20:57 -0000 1.6
+++ distrib/armish/ramdisk/Makefile 23 Jan 2009 21:46:38 -0000
@@ -3,6 +3,7 @@
 REV= ${OSrev}
 
 TOP= ${.CURDIR}/..
+LIBC=           ${TOP}/../../lib/libc
 
 BSD_RD= bsd.rd
 IMAGE= mr.fs
@@ -71,7 +72,7 @@
  -vnconfig -u ${VND}
 
 rdsetroot: ${TOP}/../common/elfrdsetroot.c
- ${HOSTCC} -o rdsetroot ${TOP}/../common/elfrdsetroot.c
+ ${HOSTCC} -DSKIP_ARCH_CHECK -o rdsetroot ${TOP}/../common/elfrdsetroot.c  ${LIBC}/gen/nlist.c
 
 unconfig:
  -umount -f ${MOUNT_POINT}
Index: lib/libc/gen/nlist.c
===================================================================
RCS file: /cvs/src/lib/libc/gen/nlist.c,v
retrieving revision 1.53
diff -u -u -r1.53 nlist.c
--- lib/libc/gen/nlist.c 4 Jun 2008 21:12:50 -0000 1.53
+++ lib/libc/gen/nlist.c 23 Nov 2008 19:00:51 -0000
@@ -286,9 +286,11 @@
     ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
     ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
 
+#ifndef SKIP_ARCH_CHECK
  /* Now check the machine dependant header */
  if (ehdr->e_machine == ELF_TARG_MACH &&
     ehdr->e_version == ELF_TARG_VER)
+#endif
  retval = 1;
  }
 

save the following into a file called armmake and make it executeable
It sets up the environment for each invocation of 'armmake'
There is a problem that 'armmake obj' doesn't work as desired, but
generally those are set up by the initial Makefile.cross build of the tools.
----
#! /bin/ksh
HOST=$(uname -m)
MACHINE=armish
MACHINE_ARCH=arm
VERSION=4.5

export MAKEOBJDIR=obj.${HOST}.${MACHINE}

TARGET_CANON=${MACHINE_ARCH}-unknown-openbsd${VERSION}
CROSSDIR=/usr/cross/${MACHINE}
PATH=$PATH:${CROSSDIR}/usr/${TARGET_CANON}/bin

MACHINE=${MACHINE} \
MACHINE_ARCH=${MACHINE_ARCH} \
CROSSDIR=${CROSSDIR} \
CC=${TARGET_CANON}-cc \
CXX=${TARGET_CANON}-c++ \
CPP=${TARGET_CANON}-cpp \
AS=${TARGET_CANON}-as \
LD=${TARGET_CANON}-ld \
SIZE=size \
STRIP=${TARGET_CANON}-strip \
OBJDUMP=${TARGET_CANON}-objdump \
OBJCOPY=${TARGET_CANON}-objcopy \
make \
MACHINE=${MACHINE} \
MACHINE_ARCH=${MACHINE_ARCH} \
MAKEOBJDIR=obj.${HOST}.${MACHINE} \
"$@"


#OBJMACHINE=${MACHINE_ARCH} \
----


Dale Rahn drahn@...