COMPAT_BSDOS(8) | System Manager's Manual | COMPAT_BSDOS(8) |
compat_bsdos
—
binary compatibility for BSDi releases
The COMPAT_NOMID
kernel option includes
compatibility with
BSDi 1.x–3.x
a.out(5) binaries on
NetBSD/i386 and
NetBSD/amd64. The option is enabled by default in
the GENERIC
kernel on i386, but needs to be set
along with EXEC_AOUT
on amd64.
Null memory protection must be disabled with the
sysctl(7) option
vm.user_va0_disable set to 0
for the binaries to run successfully.
BSD/OS binaries may be placed under /emul directory to match the location of other non-native executables on NetBSD, but the compatibility environment does not automatically lookup libraries under /emul/bsdos as happens with the shared libraries for NetBSD 1.0–1.5 a.out(5) binaries under /emul/aout.
BSD/386 1.0–1.1 uses static binaries that do not dynamically load libraries at runtime.
BSD/OS 2.0 introduced “static shared libraries” as the default for standard binaries. The shared libraries are compiled from /lib and /usr/lib to a custom format bound to memory loading addresses for each library under /shlib. BSDi libraries under /shlib are not in the standard ar(5) or position-independent shared object formats and cannot be loaded by ldconfig(8) on NetBSD. In order for BSDi executables to access the objects at the hardcoded /shlib path, the user may setup a symbolic link from /shlib to /emul/bsdos/shlib.
BSD/OS 4.0 switched to an ELF binary executable format that does not run under the compatibility layers currently available on NetBSD.
ld.aout_so(1), options(4), a.out(5), elf(5), sysctl(7), compat_netbsd32(8), ldconfig(8)
BSD/386 1.0–1.1 was derived from 4.3BSD Reno code in the Net/2 release.
BSD/OS 2.0 was based on
4.4BSD Lite, but added the new static shared library
format as the runtime default for executables. The build system included the
shlicc
command with the
-Bstatic
flag that allowed reverting to the standard
library archive format that remained available under
/lib and /usr/lib.
NetBSD 1.0 added shared libraries using a standard position-independent shared object format. The previous default relocatable libraries in the traditional ar(5) format remained available.
OpenBSD 2.2–4.7 included a
different compatibility implementation under the
COMPAT_BSDOS
kernel option.
BSD/OS compatibility was broken on NetBSD 5–6.
BSD/OS 3.0 added SPARC support, but the binaries are incorrectly recognized as SunOS executables and fail on NetBSD/sparc and NetBSD/sparc64.
August 27, 2020 | NetBSD 10.99 |