NetBSD and the experimental Darwin binary compatibility

This is a work in progress, attempting to run some mach-o binaries on NetBSD (macppc in this case).

Appeared as a significant change in NetBSD 3.0 (Support for MacOS X.3 binaries. [manu 20040825]).
"compat_darwin(8) emulation now supports Mac OS X version 10.3 binaries" was announced.

Kernel stuff


Building the kernel with darwin support

Assuming you have set a default proper environment for compiling your kernel:
In the /usr/src/sys/arch/<your ARCH>/conf/<your CONFIG>

At least, you have to enable these options:

options COMPAT_DARWIN # Darwin binary compatibility (experimental)
options COMPAT_MACH # Mach compatibility, needed for COMPAT_DARWIN 
options EXEC_MACHO # Mach-O binary support, needed for COMPAT_MACH

Optionnaly, uncomment the following:

#options DEBUG_DARWIN # COMPAT_DARWIN debugging
#options DEBUG_MACH # COMPAT_MACH debugging

After editing your configuration file, you can begin to build the kernel:

cd /usr/src/sys/arch/<your ARCH>/conf/
config <your CONFIG>
cd ../compile/<your CONFIG>
make depend
cp /netbsd /netbsd.old
cp netbsd /netbsd

Then reboot..

Problem: The build fails in darwin_commpage_machdep.S with this kind of errors:
Assembler messages:
Error: bad expression
Error: syntax error; found `4' but expected `,'
Error: junk at end of line: `4,0'
Error: bad expression
Solution: You need to remove all "%" character before each asm register names (e.g.; %r4 should become r4) in the problematic file, then redo all the necessary steps from the beginning to build the kernel

sysctl interface

By default:
sysctl -a | grep darwin = 0
emul.darwin.ioframebuffer.unit = 0
emul.darwin.ioframebuffer.screen = 0
emul.darwin.iohidsystem.mux = 0

In the source code of darwin_sysctl.c, we can read:
 * On Darwin, mach_init is the system bootstrap process. It is responsible
 * for forking the traditional UNIX init(8) and it does the Mach port naming
 * service. We need mach_init for the naming service, but unfortunately, it
 * will only act as such if its PID is 1. We use a sysctl
 * ( to fool a given process into thinking its PID is 1.
 * That way we can run mach_init when we want to.
 * Typical use:
 * sysctl -w$$; exec /emul/darwin/sbin/mach_init
 * The same problem exists after mach_init has forked init: the fork libc stub
 * really insist on the child to have PID 2 (if PID is not 2, then the stub
 * will issue bootstrap calls to an already running mach_init, which fails,
 * of course).


"These libraries are part of the Darwin compatibility option for
NetBSD/powerpc and NetBSD/i386.

The kernel options `EXEC_MACHO', `COMPAT_MACH' and `COMPAT_DARWIN'
must be in your kernel config file for this to work.from /usr/pkgsrc/emulators/darwin_lib/DESCR

cd /usr/pkgsrc/emulators/darwin_lib/
make install clean

If the build fails, you will probably need to edit /usr/pkgsrc/emulators/darwin_lib/Makefile and remove the problematic (XFree86) missing rpm in DISTFILES variable.

Attempt to run a mach-o binary

No mach_init is present by default, and mach_init has been dropped...

sysctl -w$$ && exec /emul/darwin/sbin/mach_init

At the root of a mounted old darwin iso (ppc), populate the darwin userland shadow root:
scp  -r bin sbin usr <NetBSD macppc host>:/emul/darwin
scp  -r System/Library <NetBSD macppc host>:/emul/darwin/System

The process in `ps aux':

root 412  0.0  0.0   0     0 ttyE0 RW+        - 0:00.00 /emul/darwin/sbin/mach_init 


cd /emul/darwin
./usr/bin/uname -a

same state..

root 421  0.0  0.0   0     0 ttyp0 RW+        - 0:00.00 ./usr/bin/uname -a 


At this time, darwinppc-141, OpenDarwin6.6.2, darwin-701PPC and darwinx86-801 binaries has been tested without any success.
Note: It seems memory is not allocated, an the RW+ status seems curious.

Please, let us know if you have a solution.