125 lines
4.6 KiB
Plaintext
125 lines
4.6 KiB
Plaintext
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What it is
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==========
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This is a project that Sean Eric Fagan (sef@kithrup.com) started, and
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Soren Schmidt (sos@login.dknet.dk, author of syscons) picked up. It allows
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SYSVr3.2 i386 binaries (iBCS2 compatible) to run under FreeBSD-2.0.
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We haven't been able to do an exhaustive test, of course, but we are able
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to run at least the following programs:
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ISC 2.2 sh, vi, dd, date, wc, chmod, etc.
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SCO 3.2v2 runs most (coff) utils on a chroot'ed filesystem
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Informix-2.10, gcc, bash, tcsh ....
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SCO 3.2v4 sh, gzip, GNU make, tcsh
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Some of those, for both ISC and SCO, used the shared libraries that are
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available for those systems. Currently, the only way to run them, is to
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get a copy of the shared libraries in question (e.g. /shlib/libc_s).
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There might be a way to generate them from a package available for Linux,
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but we haven't had the time or energy to do it ourself, and the last call
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for volunteers resulted in nothing. If someone else wants to volunteer,
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we would be grateful.
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How to get it into the system
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=============================
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There are two ways of getting iBCS2 support into the system. One is to use
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Loadable Kernel Modules (LKM) to put it into the kernel at run-time. This
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demands a kernel compiled with:
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options "COMPAT_IBCS2"
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This puts in the nessesary hooks to let the iBCS2 support do its thing.
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One loads the iBCS2 support by using the command 'ibcs2' (in /usr/bin).
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You can use 'modstat' to see the loaded modules.
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Another way is to compile it into the kernel. This is accomplished using:
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options "COMPAT_IBCS2"
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options "IBCS2"
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in the kernel config file.
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Where's what
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============
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The ibcs2 package consists of quite a few files located in ./sys/i386/ibcs2.
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Here is a brief description of them:
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ibcs2.h: Basic header file defines iBCS2 types etc.
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ibcs2_dummy.c: Stubs to system calls not yet supported, or not feasible
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to emulate.
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ibcs2_ioctl.c: Probably the single-most complicated part of it, this deals
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with translating as many ioctl calls as possible between
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BSD and iBCS2.
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ibcs2_misc.c: This has all of the wrapping routines that were thought
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"easy" (at least initially) or that didn't fit anywhere else.
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ibcs2_file.c: Functions that deals with file I/O, such as getdents and read
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which are more complex than one should expect.
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ibcs2_signal.c: This deals with the signal cruft, including both system
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calls and signal translation.
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ibcs2_stats.c: This has all of the filesystem statistic wrappers
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(stat, fstat, statfs, etc.).
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ibcs2_sysent.c: This has the system call table for iBCS2 programs, and is
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NOT generated automatically.
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ibcs2_ipc.c: Stubs for the iBCS2 ipc calls (shm, msg, sem).
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ibcs2_isc.c: This deals with the ISC specific system call (cisc()).
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ibcs2_sysi86.c: This deals with the i86 specific system call (sysi86()).
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ibcs2_xenix.c: This deals with the Xenix specific system call (cxenix()).
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(This also has some of SCO's POSIX-conformant functions.)
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imgact_coff.c: This is the functions that alllows the kernel to load
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COFF programs. It also deals with shared library loading.
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There also exist two files (ibcs2_socksys.[ch]) which contains a proto
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implementation of the SYSVr3 socket system, donated by Mostyn Lewis
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(mostyn@mrl.com). It has not been tested much but is included as a basis
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for network support, which is nessesary to run X and the likes.
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What's Next
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===========
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Much needs to be done yet, mainly the socksys emulation should be looked
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at to get socket support going. There currently also is no ipc support.
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The sem & msg functions should map fairly easy to the BSD ones, but our
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current BSD shm implementation is not even close to SYSV behavior, if it
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works at all.
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We currently have loaders or "image_activators" for other binary formats,
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but none of them is really usefull yet (xout, elf).
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Also most of the wrappers for the extra syscalls used by SYSVr4 has been
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done, but not much testing yet because of lacks in the elf loader (but it
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will run a statically linked SYSVr4 shell).
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All the wrappers should be tested one by one using every aspect of use
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by the iBCS2 system. The tests we have done so far is to run small
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testprograms to check a limited set of the emulation. When this proved
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that the basics was functional, we tried with what iBCS2 programs where
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at hand. This is by no means an exhaustive test or to say that the
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emulation is errorfree, only a statement of overall functionality of
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the emulator.
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Surely much work can be done here, but we are both kind of lazy, and did
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the whole thing just for the fun of it, and mainly as a "can it be done"
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project.
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Soren Schmidt (sos@login.dknet.dk)
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Sean Eric Fagan (sef@kithrup.com)
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