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发信人: Lg (创造人生的传奇), 信区: Linux
标 题: Linux under FreeBSD
发信站: BBS 荔园晨风站 (Mon Jan 3 13:42:11 2000), 站内信件
Linux under FreeBSD
Michael Lucas
FreeBSD has several options for using software from other platforms, such as
Wine for Win32 and
dosemu for DOS. BSDI, NetBSD, and OpenBSD binaries will run unmodified, and
source code
from many UNIX or Linux programs can be compiled without modification on
FreeBSD.
Additionally, FreeBSD includes kernel modules for Linux, SCO, and SVR4. These
modules allow
you to run unmodified binaries for these platforms on your FreeBSD machine.
FreeBSD's Linux
module works well enough that several commercial software packages for Linux
have been included
in the FreeBSD ports system. Similarly, this article was written on Sun
StarOffice 5.1 for Linux, on
my FreeBSD-current box. Because the last version of RealVideo for FreeBSD is
version 3.0, I run
RealVideo 5.0 for Linux.
In FreeBSD 3.3-stable or higher, Linux mode has two components: the kernel
system call module,
and the runtime environment.
The Linux Kernel Module
The kernel-loadable module, or KLM, supports Linux-specific system calls.
You can determine
whether the Linux KLM is loaded on your system by using:
#kldstat -v | grep linux
2 1 0xc08dc000 e000 linux.ko
15 linuxelf
16 linuxaout
#
(kldstat -v provides other useful information about your kernel, and is
generally informative on any
FreeBSD system.) If the module is not loaded, you can load it by becoming
root and typing:
# linux
You can make this automatic at boot by setting linux_enable="YES" in /etc
/rc.conf. Strictly
speaking, you don't have to compile a custom kernel to support the Linux
module. You'll be more
satisfied with your results, however, if your kernel includes the following
options:
options "P1003_1B" #POSIX infrastructure
options "_KPOSIX_PRIORITY_SCHEDULING" #Built-in POSIX priority scheduling
options "_KPOSIX_VERSION=199309L" #POSIX version kernel is built for
options SYSVSHM #System V shared memory
options SYSVMSG #System V semaphores
options SYSVSEM #System V messaging
options USER_LDT #allow user-level control of i386 ldt
For full instructions on building a custom kernel, check:
http://www.FreeBSD.org/handbook/handbook50.html
If you have the FreeBSD docs installed on your local system, see:
/usr/share/doc/handbook/handbook50.html
The kernel emulator does have a small overhead, but it is negligible. If
you're interested in the details
and don't feel like reading the source code, search for "overhead" in the
freebsd-emulation mailing
list archives (http://www.FreeBSD.org/search/).
Runtime Environment
Dynamically linked Linux binaries expect to have certain libraries available.
Linux has a variety of
library sets, such as libc4, libc5, and glibc2. Additionally, some Linux
programs expect to have
particular Linux userland programs available (sh, test, etc.) Because FreeBSD
uses the same
codebase as original UNIX, whereas Linux was written from scratch, these may
not be 100%
compatible. A selection of Linux userland utilities can also be helpful,
especially when dealing with
closed-source commercial software products.
The dynamic libraries and Linux userland utilities are available as a port.
Look under
/usr/ports/emulators/linux_base for the latest stable version. Install these
as you would any other
port:
#cd /usr/ports/emulators/linux_base
#make install
The port installs a subset of Red Hat Linux's userland under /compat/linux.
The original source files (or "distfiles", in FreeBSD parlance) are quite
large. You will probably want
to load these from a FreeBSD CD, a Red Hat CD, or from behind a large
Internet circuit. If you're
downloading over a 56 Kb modem, I'd recommend doing this when you don't plan
to use your 'Net
connection for several hours. The linux_base port installs everything under
/compat/linux. If you're
curious, do an ls:
#ls
bin boot etc lib mnt proc sbin usr var
#
This looks suspiciously like a subset of the root directory. /compat/linux
contains resources for
Linux binaries that expect to find different resources than those available
on a FreeBSD machine.
While it's not chrooted, it's built in a similar manner.
For example, on a Linux machine the file /etc/nsswitch.conf contains vital
configuration information.
FreeBSD keeps that information elsewhere. Any program run under Linux mode
will check
/compat/linux/etc for a system config file, and then fall back to /etc.
Linux Distributions and Emulation
At the moment, FreeBSD's Linux mode is based on Red Hat 5.2. (RedHat 6.0
emulation is in
-current, and should be backported to -stable by the time you read this.)
This doesn't mean that
you can't use software designed for other distributions, however.
Using a particular Red Hat distribution simply indicates the level of Linux
kernel and userland library
support available in your FreeBSD system. Red Hat 5.2 uses libc5, glibc2,
and Linux kernel
2.0.36. RedHat 6.0 uses glibc2.1 and kernel 2.2.5. Linux software that will
run under these
libraries, and this kernel will work in FreeBSD's Linux mode.
Running Linux Apps
When you have the linux_base port installed, and kldstat -v shows the Linux
module is running,
just run your Linux program from a command prompt.
Adding Linux Libraries
FreeBSD's install routines and ports system take care of almost all the ugly
details of configuring
shared libraries, insulating the administrator from the majority of these
issues. This system does not
cover software from other operating systems running under kernel modules.
Linux systems tend to
accumulate shared libraries like pocket lint. Eventually, you'll need to
add additional Linux shared
libraries to your system.
The Linux emulator has its own ldconfig, /compat/linux/sbin/ldconfig, and
its own ld.so.conf file,
/compat/linux/etc/ld.so.conf. If you look at this file, you'll see:
#more ld.so.conf
/usr/X11R6/lib
/usr/i486-linux-libc5/lib
#
These are the directories where the module will look for Linux libraries,
in addition to /lib and
/usr/lib. Despite the initial slash, these directory names are all under
/compat/linux. I recommend
installing additional libraries under /compat/linux/usr/local/lib. Edit
/compat/linux/etc/ldconfig.conf to add this path. When you have large
programs that include
many libraries of their own, you might wish to create new directories for
those shared libraries. My
/compat/linux/etc/ld.so.conf looks like:
#more ld.so.conf
/usr/local/lib
/usr/local/lib/soffice
/usr/X11R6/lib
/usr/i486-linux-libc5/lib
/usr/openwin/lib
#
Whenever you add new libraries, rerun /compat/linux/sbin/ldconfig. This
rereads the directories in
the configuration file and updates the list of available libraries. Be sure
you run
/compat/linux/sbin/ldconfig, and not FreeBSD's /sbin/ldconfig. Not only will
the FreeBSD
ldconfig not accomplish what you want, you'll find yourself either digging
through /etc/rc.* scripts to
learn how to properly reconfigure your shared library cache or simply
rebooting in annoyance.
When a Linux program fails because it cannot find a library, check to be sure
you have the library. If
you don't have it, call up your favorite Internet search engine and fetch a
copy. Install it in
/compat/linux/usr/local/lib, run Linux ldconfig, and you'll be up and running.
Alternately, you can use the environment variable LD_LIBRARY_PATH to tell a
shell to check a
particular directory for libraries (see man 8 ldconfig). Many problems can
be caused by the
indiscriminate use of LD_LIBRARY_PATH, however, so you're better off editing
/usr/compat/linux/etc/ld.so.conf.
Installing Linux Software as FreeBSD Ports
Some Linux software packages are available via FreeBSD's ports system. One
well-known
example is WordPerfect 8. If you become root, cd /usr/ports/editors
/wordperfect, and type
make, you will get:
#make
===> wordperfect-8.0 'The source to this
port may not be automatically fetched due
to licensing restrictions. You MUST fetch
the source manually after reading and
agreeing to the license at:
http://linux.corel.com/linux8/download.htm
Once GUILG00.GZ has been downloaded, move
it to /usr/ports/distfiles and then restart
this build.'.
#
In this case, FreeBSD's automatic fetch mechanism won't work - WordPerfect's
distribution terms
require the user to agree to a license before downloading. Go to the Web page,
accept their terms,
and download WordPerfect. Install the file in /usr/ports/distfiles, return to
/usr/ports/editors/wordperfect, and type make. The port will automatically
install WordPerfect
for you.
Linux Packages
One of the tools linux_base installs is Red Hat's RPM. You can use this to
install RPMs on your
FreeBSD machine. When using RPMs, you will want to be certain to install the
software under
/compat/linux. Because of FreeBSD's monolithic upgrade procedure (see my
article "Maintaining
Patch Levels in Open-Source BSDs, Sys Admin, September 1999), any RPM
components that
overwrite system components will be blown away the next time you upgrade.
If you overwrite the
wrong files, your system might even become unbootable. To install an RPM,
do:
rpm -i -ignoreos -dbpath /var/lib/rpm -root \
/compat/linux [package]
Add other RPM flags as desired. Of course, RPM packages are completely
separate from
FreeBSD's usual package system. Do not expect to be able to pkg_delete these;
you will need to
use rpm to handle them.
Be very careful in your use of RPM; if you accidentally overwrite part of
your FreeBSD installation
with Linux binaries, you can expect to find yourself booting off CD-ROM to
restore your system.
(The Linux module is good, but not that good.) If you're using a Linux
program built into a FreeBSD
package, such as linux_glide, you can use the standard FreeBSD pkg_add pkgname.
Manual Installations
Even with FreeBSD's excellent package management, some software has to be
installed the hard
way, by hand. I'll use Sun's StarOffice 5.1 as an example. Rather than
provide a specific set of
instructions on how to install this particular application, we'll
troubleshoot a typical closed-source,
Linux-binary software installation.
You can download StarOffice at www.stardivision.com. A full download runs
about 70 megs, so
you might wish to spend the $10 for a CD-ROM. Copy the file so51a_lnx_01.tar
to your home
directory and untar it.
After decompressing, cd so51inst/bin and run ./setup. At this point, you
might get a warning about
/tmp being full. StarOffice is a huge office suite. If you run out of space,
you will need to repoint
your tmp directory. The easiest way to do this is with the environment
variable $TMPDIR. Point
TMPDIR at a directory with a lot of space, and try again.
You'll see:
#./setup
./setup: Window manager didn't set icon sizes - using default.
/tmp/sv001.tmp/setup.bin: error in loading shared libraries
libvos517li.so: cannot open shared object file: No such file or directory
#
This is a shared library problem, as described above. You can simply do:
#LD_LIBRARY_PATH=/tmp/sv001.tmp ; export LD_LIBRARY_PATH
Rerun the setup routine. This time, it will open a nice GUI window, ask you
some questions, and
install itself. After the install, look in "Office51/bin" under your home
directory. Typing ./soffice&
will bring up StarOffice. I use a simple shell script:
#!/bin/sh
/home/mwlucas/Office51/bin/soffice&
If you are interested in server applications, you should take a look at "How
to run Oracle for Linux
on FreeBSD," available at:
http://www.scc.nl/~marcel/howto-oracle.html
Problems
Any number of things can go wrong with a software install, let alone one
running on a platform it
wasn't built for. Some programs will require branding before you can run
them. Branding a binary
leaves an ELF comment that the kernel uses to choose an ABI. brandelf
programname will tell
you which ABI a program thinks it needs. You can use brandelf -t linux
programname to
manually point a binary at the Linux module. (SysV binaries do not use
branding.)
If the program complains about unsupported functions, check your kernel
config. Do you have the
POSIX and SysV options configured? Check kldstat -v to confirm the Linux
module is loaded. If
the above fails, your first resource should be the FreeBSD mailing list
archives. Look at:
http://www.FreeBSD.org/search.html
Unless you're the first person in the world to have a problem with this
piece of software, you'll find
an archived question about it. The "questions" and "emulation" archives
are excellent places to
search.
If the mailing lists archives don't help, send a message to
freebsd-questions@FreeBSD.org. Be
sure to give the version of FreeBSD you have, the version of linux_base
you're using, and any and
all details about the program you're trying to run, including any error
messages when you try to run
it. If it's an obvious problem, someone will probably answer you quickly.
For more difficult
problems, you might be directed to the freebsd-emulation mailing list.
If you find yourself using Linux emulation more and more frequently, you
would find it worthwhile to
subscribe to the freebsd-emulation mailing list. Email majordomo@FreeBSD.org
with a body of
"subscribe freebsd-emulation".
Conclusion
FreeBSD's Linux mode gives FreeBSD users access to a wide variety of
commercial software
packages. I encourage you to contact any software vendor that does not offer
a FreeBSD version
of a desired program and let them know you would purchase a native version.
Vendors don't realize
that demand exists unless someone tells them. Although good for your karma,
these requests won't
help you listen to espn.com's daily broadcasts on your computer. Combined
with the SVR4 and
SCO kernel modules, the Linux module gives you access to almost the entire
range of UNIX
software on your FreeBSD box. n
About the Author
Michael Lucas is a networking and FreeBSD consultant working for the Great
Lakes
Technologies Group. He lives in Detroit, Michigan with his wife Liz, four
gerbils, and
assorted fish. He can be reached at: mwlucas@exceptionet.com.
--
☆ 来源:．BBS 荔园晨风站 bbs.szu.edu.cn．[FROM: bbs@202.104.97.128]
※ 修改:·georgehill 於 Jan 3 15:35:18 修改本文·[FROM: 192.168.1.115]
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