Contributed by &a.handy; and &a.rich; Linux emulation in FreeBSD has reached a point where it is possible to run a large fraction of Linux binaries in both a.out and ELF format. The linux emulation in the 2.1-STABLE branch is capable of running Linux DOOM and Mathematica; the version present in &rel.current;-RELEASE is vastly more capable and runs all these as well as Quake, Abuse, IDL, netrek for Linux and a whole host of other programs. There are some Linux-specific operating system features that are not supported on FreeBSD. Linux binaries will not work on FreeBSD if they use the Linux /proc filesystem (which is different from the optional FreeBSD /proc filesystem) or i386-specific calls, such as enabling virtual 8086 mode. Depending on which version of FreeBSD you are running, how you get Linux-emulation up will vary slightly: The GENERIC kernel in 2.1-STABLE is not configured for linux compatibility so you must reconfigure your kernel for it. There are two ways to do this: 1. linking the emulator statically in the kernel itself and 2. configuring your kernel to dynamically load the linux loadable kernel module (LKM). To enable the emulator, add the following to your configuration file (c.f. /sys/i386/conf/LINT): options COMPAT_LINUX If you want to run doom or other applications that need shared memory, also add the following. options SYSVSHM The linux system calls require 4.3BSD system call compatibility. So make sure you have the following. options "COMPAT_43" If you prefer to statically link the emulator in the kernel rather than use the loadable kernel module (LKM), then add options LINUX Then run config and install the new kernel as described in the kernel configuration section. If you decide to use the LKM you must also install the loadable module. A mismatch of versions between the kernel and loadable module can cause the kernel to crash, so the safest thing to do is to reinstall the LKM when you install the kernel. &prompt.root; cd /usr/src/lkm/linux &prompt.root; make all install Once you have installed the kernel and the LKM, you can invoke `linux' as root to load the LKM. &prompt.root; linux Linux emulator installed Module loaded as ID 0 To see whether the LKM is loaded, run modstat. &prompt.user; modstat Type Id Off Loadaddr Size Info Rev Module Name EXEC 0 3 f0baf000 0018 f0bb4000 1 linux_emulator You can cause the LKM to be loaded when the system boots in either of two ways. In FreeBSD 2.2.1-RELEASE and 2.1-STABLE enable it in /etc/sysconfig linux=YES by changing it from NO to YES. FreeBSD 2.1 RELEASE and earlier do not have such a line and on those you will need to edit /etc/rc.local to add the following line. linux It is no longer necessary to specify options LINUX or options COMPAT_LINUX. Linux emulation is done with an LKM (“Loadable Kernel Module”) so it can be installed on the fly without having to reboot. You will need the following things in your startup files, however: In /etc/rc.conf, you need the following line: linux_enable=YES This, in turn, triggers the following action in /etc/rc.i386: # Start the Linux binary emulation if requested. if [ "X${linux_enable}" = X"YES" ]; then echo -n ' linux'; linux > /dev/null 2>&1 fi If you want to verify it is running, modstat will do that: &prompt.user; modstat Type Id Off Loadaddr Size Info Rev Module Name EXEC 0 4 f09e6000 001c f09ec010 1 linux_mod However, there have been reports that this fails on some 2.2-RELEASE and later systems. If for some reason you cannot load the linux LKM, then statically link the emulator in the kernel by adding options LINUX to your kernel config file. Then run config and install the new kernel as described in the kernel configuration section. Most linux applications use shared libraries, so you are still not done until you install the shared libraries. It is possible to do this by hand, however, it is vastly simpler to just grab the linux_lib port: &prompt.root; cd /usr/ports/emulators/linux_lib &prompt.root; make all install and you should have a working linux emulator. Legend (and the mail archives :-) seems to hold that Linux emulation works best with linux binaries linked against the ZMAGIC libraries; QMAGIC libraries (such as those used in Slackware V2.0) may tend to give the Linuxulator heartburn. Also, expect some programs to complain about incorrect minor versions of the system libraries. In general, however, this does not seem to be a problem. If you do not have the “ports” distribution, you can install the libraries by hand instead. You will need the Linux shared libraries that the program depends on and the runtime linker. Also, you will need to create a "shadow root" directory, /compat/linux, for Linux libraries on your FreeBSD system. Any shared libraries opened by Linux programs run under FreeBSD will look in this tree first. So, if a Linux program loads, for example, /lib/libc.so, FreeBSD will first try to open /compat/linux/lib/libc.so, and if that does not exist then it will try /lib/libc.so. Shared libraries should be installed in the shadow tree /compat/linux/lib rather than the paths that the Linux ld.so reports. FreeBSD-2.2-RELEASE and later works slightly differently with respect to /compat/linux: all files, not just libraries, are searched for from the “shadow root” /compat/linux. Generally, you will need to look for the shared libraries that Linux binaries depend on only the first few times that you install a Linux program on your FreeBSD system. After a while, you will have a sufficient set of Linux shared libraries on your system to be able to run newly imported Linux binaries without any extra work. What if you install the linux_lib port and your application still complains about missing shared libraries? How do you know which shared libraries Linux binaries need, and where to get them? Basically, there are 2 possibilities (when following these instructions: you will need to be root on your FreeBSD system to do the necessary installation steps). If you have access to a Linux system, see what shared libraries the application needs, and copy them to your FreeBSD system. Example: you have just ftp'ed the Linux binary of Doom. Put it on the Linux system you have access to, and check which shared libraries it needs by running ldd linuxxdoom: &prompt.user; ldd linuxxdoom libXt.so.3 (DLL Jump 3.1) => /usr/X11/lib/libXt.so.3.1.0 libX11.so.3 (DLL Jump 3.1) => /usr/X11/lib/libX11.so.3.1.0 libc.so.4 (DLL Jump 4.5pl26) => /lib/libc.so.4.6.29 You would need to get all the files from the last column, and put them under /compat/linux, with the names in the first column as symbolic links pointing to them. This means you eventually have these files on your FreeBSD system: /compat/linux/usr/X11/lib/libXt.so.3.1.0 /compat/linux/usr/X11/lib/libXt.so.3 -> libXt.so.3.1.0 /compat/linux/usr/X11/lib/libX11.so.3.1.0 /compat/linux/usr/X11/lib/libX11.so.3 -> libX11.so.3.1.0 /compat/linux/lib/libc.so.4.6.29 /compat/linux/lib/libc.so.4 -> libc.so.4.6.29 Note that if you already have a Linux shared library with a matching major revision number to the first column of the ldd output, you will not need to copy the file named in the last column to your system, the one you already have should work. It is advisable to copy the shared library anyway if it is a newer version, though. You can remove the old one, as long as you make the symbolic link point to the new one. So, if you have these libraries on your system: /compat/linux/lib/libc.so.4.6.27 /compat/linux/lib/libc.so.4 -> libc.so.4.6.27 and you find a new binary that claims to require a later version according to the output of ldd: libc.so.4 (DLL Jump 4.5pl26) -> libc.so.4.6.29 If it is only one or two versions out of date in the in the trailing digit then do not worry about copying /lib/libc.so.4.6.29 too, because the program should work fine with the slightly older version. However, if you like you can decide to replace the libc.so anyway, and that should leave you with: /compat/linux/lib/libc.so.4.6.29 /compat/linux/lib/libc.so.4 -> libc.so.4.6.29 The symbolic link mechanism is only needed for Linux binaries. The FreeBSD runtime linker takes care of looking for matching major revision numbers itself and you do not need to worry about it. This section applies only to FreeBSD 2.2-RELEASE and later. Those running 2.1-STABLE should skip this section. Finally, if you run FreeBSD 2.2-RELEASE you must make sure that you have the Linux runtime linker and its config files on your system. You should copy these files from the Linux system to their appropriate place on your FreeBSD system (to the /compat/linux tree): /compat/linux/lib/ld.so /compat/linux/etc/ld.so.config If you do not have access to a Linux system, you should get the extra files you need from various ftp sites. Information on where to look for the various files is appended below. For now, let us assume you know where to get the files. Retrieve the following files (all from the same ftp site to avoid any version mismatches), and install them under /compat/linux (i.e. /foo/bar is installed as /compat/linux/foo/bar): /sbin/ldconfig /usr/bin/ldd /lib/libc.so.x.y.z /lib/ld.so ldconfig and ldd do not necessarily need to be under /compat/linux; you can install them elsewhere in the system too. Just make sure they do not conflict with their FreeBSD counterparts. A good idea would be to install them in /usr/local/bin as ldconfig-linux and ldd-linux. Create the file /compat/linux/etc/ld.so.conf, containing the directories in which the Linux runtime linker should look for shared libs. It is a plain text file, containing a directory name on each line. /lib and /usr/lib are standard, you could add the following: /usr/X11/lib /usr/local/lib When a linux binary opens a library such as /lib/libc.so the emulator maps the name to /compat/linux/lib/libc.so internally. All linux libraries should be installed under /compat/linux (e.g. /compat/linux/lib/libc.so, /compat/linux/usr/X11/lib/libX11.so, etc.) in order for the emulator to find them. Those running FreeBSD 2.2-RELEASE should run the Linux ldconfig program. &prompt.root cd /compat/linux/lib &prompt.root; /compat/linux/sbin/ldconfig ldconfig is statically linked, so it does not need any shared libraries to run. It creates the file /compat/linux/etc/ld.so.cache which contains the names of all the shared libraries and should be rerun to recreate this file whenever you install additional shared libraries. On 2.1-STABLE do not install /compat/linux/etc/ld.so.cache or run ldconfig; in 2.1-STABLE the syscalls are implemented differently and ldconfig is not needed or used. You should now be set up for Linux binaries which only need a shared libc. You can test this by running the Linux ldd on itself. Supposing that you have it installed as ldd-linux, it should produce something like: &prompt.root; ldd-linux `which ldd-linux` libc.so.4 (DLL Jump 4.5pl26) => /lib/libc.so.4.6.29 This being done, you are ready to install new Linux binaries. Whenever you install a new Linux program, you should check if it needs shared libraries, and if so, whether you have them installed in the /compat/linux tree. To do this, you run the Linux version ldd on the new program, and watch its output. ldd (see also the manual page for ldd1) will print a list of shared libraries that the program depends on, in the form majorname (jumpversion) => fullname. If it prints not found instead of fullname it means that you need an extra library. The library needed is shown in majorname and will be of the form libXXXX.so.N. You will need to find a libXXXX.so.N.mm on a Linux ftp site, and install it on your system. The XXXX (name) and N (major revision number) should match; the minor number(s) mm are less important, though it is advised to take the most recent version. ELF binaries sometimes require an extra step of “branding”. If you attempt to run an unbranded ELF binary, you will get an error message like the following; &prompt.user; ./my-linux-elf-binary ELF binary type not known Abort To help the FreeBSD kernel distinguish between a FreeBSD ELF binary from a Linux one, use the brandelf 1 utility. &prompt.user; brandelf -t Linux my-linux-elf-binary The GNU toolchain now places the appropriate branding information into ELF binaries automatically, so you should be needing to do this step increasingly rarely in future. If DNS does not work or you get the messages resolv+: "bind" is an invalid keyword resolv+: "hosts" is an invalid keyword then you need to configure a /compat/linux/etc/host.conf file containing: order hosts, bind multi on where the order here specifies that /etc/hosts is searched first and DNS is searched second. When /compat/linux/etc/host.conf is not installed linux applications find FreeBSD's /etc/host.conf and complain about the incompatible FreeBSD syntax. You should remove bind if you have not configured a name-server using the /etc/resolv.conf file. Lastly, those who run 2.1-STABLE need to set an the RESOLV_HOST_CONF environment variable so that applications will know how to search the host tables. If you run FreeBSD 2.2-RELEASE or later, you can skip this. For the /bin/csh shell use: &prompt.user; setenv RESOLV_HOST_CONF /compat/linux/etc/host.conf For /bin/sh use: &prompt.user; RESOLV_HOST_CONF=/compat/linux/etc/host.conf; export RESOLV_HOST_CONF The information below is valid as of the time this document was written, but certain details such as names of ftp sites, directories and distribution names may have changed by the time you read this. Linux is distributed by several groups that make their own set of binaries that they distribute. Each distribution has its own name, like “Slackware” or “Yggdrasil”. The distributions are available on a lot of ftp sites. Sometimes the files are unpacked, and you can get the individual files you need, but mostly they are stored in distribution sets, usually consisting of subdirectories with gzipped tar files in them. The primary ftp sites for the distributions are: sunsite.unc.edu:/pub/Linux/distributions tsx-11.mit.edu:/pub/linux/distributions Some European mirrors: ftp.luth.se:/pub/linux/distributions ftp.demon.co.uk:/pub/unix/linux src.doc.ic.ac.uk:/packages/linux/distributions For simplicity, let us concentrate on Slackware here. This distribution consists of a number of subdirectories, containing separate packages. Normally, they are controlled by an install program, but you can retrieve files “by hand” too. First of all, you will need to look in the contents subdir of the distribution. You will find a lot of small text files here describing the contents of the separate packages. The fastest way to look something up is to retrieve all the files in the contents subdirectory, and grep through them for the file you need. Here is an example of a list of files that you might need, and in which contents-file you will find it by grepping through them: Library Package ld.so ldso ldconfig ldso ldd ldso libc.so.4 shlibs libX11.so.6.0 xf_lib libXt.so.6.0 xf_lib libX11.so.3 oldlibs libXt.so.3 oldlibs So, in this case, you will need the packages ldso, shlibs, xf_lib and oldlibs. In each of the contents-files for these packages, look for a line saying PACKAGE LOCATION, it will tell you on which “disk” the package is, in our case it will tell us in which subdirectory we need to look. For our example, we would find the following locations: Package Location ldso diska2 shlibs diska2 oldlibs diskx6 xf_lib diskx9 The locations called “diskXX” refer to the slakware/XX subdirectories of the distribution, others may be found in the contrib subdirectory. In this case, we could now retrieve the packages we need by retrieving the following files (relative to the root of the Slackware distribution tree): slakware/a2/ldso.tgz slakware/a2/shlibs.tgz slakware/x6/oldlibs/tgz slakware/x9/xf_lib.tgz Extract the files from these gzipped tarfiles in your /compat/linux directory (possibly omitting or afterwards removing files you do not need), and you are done. See also: ftp.freebsd.org:pub/FreeBSD/2.0.5-RELEASE/xperimnt/linux-emu/README and /usr/src/sys/i386/ibcs2/README.iBCS2 Contributed by &a.rich; and &a.chuck; This document shows how to install the Linux binary distribution of Mathematica 2.2 on FreeBSD 2.1. Mathematica supports Linux but not FreeBSD as it stands. So once you have configured your system for Linux compatibility you have most of what you need to run Mathematica. For those who already have the student edition of Mathematica for DOS the cost of upgrading to the Linux version at the time this was written, March 1996, was $45.00. It can be ordered directly from Wolfram at (217) 398-6500 and paid for by credit card. The binaries are currently distributed by Wolfram on CDROM. The CDROM has about a dozen tar files, each of which is a binary distribution for one of the supported architectures. The one for Linux is named LINUX.TAR. You can, for example, unpack this into /usr/local/Mathematica: &prompt.root; cd /usr/local &prompt.root; mkdir Mathematica &prompt.root; cd Mathematica &prompt.root; tar -xvf /cdrom/LINUX.TAR Before you can run Mathematica you will have to obtain a password from Wolfram that corresponds to your “machine ID”. Once you have installed the linux compatibility runtime libraries and unpacked the mathematica you can obtain the “machine ID” by running the program mathinfo in the Install directory. &prompt.root; cd /usr/local/Mathematica/Install &prompt.root; mathinfo LINUX: 'ioctl' fd=5, typ=0x89(), num=0x27 not implemented richc.isdn.bcm.tmc.edu 9845-03452-90255 So, for example, the “machine ID” of richc is 9845-03452-90255. You can ignore the message about the ioctl that is not implemented. It will not prevent Mathematica from running in any way and you can safely ignore it, though you will see the message every time you run Mathematica. When you register with Wolfram, either by email, phone or fax, you will give them the “machine ID” and they will respond with a corresponding password consisting of groups of numbers. You need to add them both along with the machine name and license number in your mathpass file. You can do this by invoking: &prompt.root; cd /usr/local/Mathematica/Install &prompt.root; math.install It will ask you to enter your license number and the Wolfram supplied password. If you get them mixed up or for some reason the math.install fails, that is OK; you can simply edit the file mathpass in this same directory to correct the info manually. After getting past the password, math.install will ask you if you accept the install defaults provided, or if you want to use your own. If you are like us and distrust all install programs, you probably want to specify the actual directories. Beware. Although the math.install program asks you to specify directories, it will not create them for you, so you should perhaps have a second window open with another shell so that you can create them before you give them to the install program. Or, if it fails, you can create the directories and then restart the math.install program. The directories we chose to create beforehand and specify to math.install were: /usr/local/Mathematica/bin for binaries /usr/local/Mathematica/man/man1 for man pages /usr/local/Mathematica/lib/X11 for the XKeysymb file You can also tell it to use /tmp/math.record for the system record file, where it puts logs of sessions. After this math.install will continue on to unpacking things and placing everything where it should go. The Mathematica Notebook feature is included separately, as the X Front End, and you have to install it separately. To get the X Front End stuff correctly installed, cd into the /usr/local/Mathematica/FrontEnd directory and execute the xfe.install shell script. You will have to tell it where to put things, but you do not have to create any directories because it will use the same directories that had been created for math.install. When it finishes, there should be a new shell script in /usr/local/Mathematica/bin called mathematica. Lastly, you need to modify each of the shell scripts that Mathematica has installed. At the beginning of every shell script in /usr/local/Mathematica/bin add the following line: &prompt.user; XKEYSYMDB=/usr/local/Mathematica/lib/X11/XKeysymDB; export XKEYSYMDB This tells Mathematica were to find its own version of the key mapping file XKeysymDB. Without this you will get pages of error messages about missing key mappings. On 2.1-STABLE you need to add the following as well: &prompt.user; RESOLV_HOST_CONF=/compat/linux/etc/host.conf; export RESOLV_HOST_CONF This tells Mathematica to use the linux version of host.conf. This file has a different syntax from FreeBSD's host.conf, so you will get an error message about /etc/host.conf if you leave this out. You might also want to modify your /etc/manpath.config file to read the new man directory, and you may need to edit your ~/.cshrc file to add /usr/local/Mathematica/bin to your path. That is about all it takes. With this you should be able to type mathematica and get a really slick looking Mathematica Notebook screen up. Mathematica has included the Motif user interfaces, but it is compiled in statically, so you do not need the Motif libraries. Good luck doing this yourself! The Notebook front end is known to hang sometimes when reading notebook files with an error messages similar to: File .../Untitled-1.mb appears to be broken for OMPR.257.0 We have not found the cause for this, but it only affects the Notebook's X Window front end, not the mathematica engine itself. So the command line interface invoked by 'math' is unaffected by this bug. A well-deserved thanks should go to &a.sos; and &a.peter; who made linux emulation what it is today, and Michael Smith who drove these two guys like dogs to get it to the point where it runs Linux binaries better than linux! :-)