406 lines
14 KiB
Groff
406 lines
14 KiB
Groff
.\" $NetBSD: compat_linux.8,v 1.11 1998/04/28 04:07:07 fair Exp $
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.\"
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.\" Copyright (c) 1995 Frank van der Linden
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed for the NetBSD Project
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.\" by Frank van der Linden
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd March 2, 1995
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.Dt COMPAT_LINUX 8
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.Os NetBSD
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.Sh NAME
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.Nm compat_linux
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.Nd setup procedure for running Linux binaries
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.Sh DESCRIPTION
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.Nx
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supports running Linux binaries. This only applies to i386 systems
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for now. Both the a.out and ELF binary formats are supported. Most programs
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should work, including the ones that use the Linux SVGAlib. Programs that
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will not work include the Linux /proc filesystem (which is different from
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the optional
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.Nx
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/proc filesystem), and i386-specific calls, such as
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enabling virtual 8086 mode. Currently, sound is only partially
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supported for Linux binaries (they will probably run, depending on
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what Linux sound support features are used).
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The Linux compatibility feature is active
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for kernels compiled with the
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.Dv COMPAT_LINUX
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option enabled.
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If support for Linux a.out executables is desired, the
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.Dv EXEC_AOUT
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option should be enabled in addition to
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.Dv COMPAT_LINUX .
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Similarly, if support for Linux 32-bit and/or 64-bit ELF executables
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is desired, the
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.Dv EXEC_ELF32
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and/or
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.Dv EXEC_ELF64
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options (respectively) should be enabled in addition to
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.Dv COMPAT_LINUX .
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.Pp
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A lot of programs are dynamically linked. This means, that you will
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also need the Linux shared libraries that the program depends on, and
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the runtime linker. Also, you will need to create a "shadow root"
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directory for Linux binaries on your
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.Nx
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system. This directory
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is named /emul/linux. Any file operations done by Linux programs
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run under
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.Nx
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will look in this directory first. So, if a Linux
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program opens, for example, /etc/passwd,
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.Nx
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will
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first try to open /emul/linux/etc/passwd, and if that does not exist
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open the 'real' /etc/passwd file. It is recommended that you install
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Linux packages that include configuration files, etc under /emul/linux,
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to avoid naming conflicts with possible
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.Nx
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counterparts. Shared
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libraries should also be installed in the shadow tree.
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.Pp
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Generally, you will need to look for the shared libraries that Linux
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binaries depend on only the first few times that you install a Linux
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program on your
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.Nx
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system. After a while, you will have a sufficient
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set of Linux shared libraries on your system to be able to run newly
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imported Linux binaries without any extra work.
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.Ss Setting up shared libraries
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How to get to know which shared libraries Linux binaries need, and where
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to get them? Basically, there are 2 possibilities (when following
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these instructions: you will need to be root on your
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.Nx
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system to
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do the necessary installation steps).
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.Bl -tag -width 123 -compact
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.It 1.
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You have access to a Linux system. In this case you can
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temporarily install the binary there, see what shared libraries
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it needs, and copy them to your
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.Nx
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system. Example: you have
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just ftp-ed the Linux binary of Doom. Put it on the Linux
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system you have access to, and check which shared libraries it
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needs by running `ldd linuxxdoom':
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.Pp
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.Bl -tag -width 123 -compact -offset indent
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.It (me@linux) ldd linuxxdoom
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.nf
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libXt.so.3 (DLL Jump 3.1) => /usr/X11/lib/libXt.so.3.1.0
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libX11.so.3 (DLL Jump 3.1) => /usr/X11/lib/libX11.so.3.1.0
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libc.so.4 (DLL Jump 4.5pl26) => /lib/libc.so.4.6.29
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.fi
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.El
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.Pp
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You would need go get all the files from the last column, and
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put them under /emul/linux, with the names in the first column
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as symbolic links pointing to them. This means you eventually have
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these files on your
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.Nx
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system:
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.Pp
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.nf
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/emul/linux/usr/X11/lib/libXt.so.3.1.0
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/emul/linux/usr/X11/lib/libXt.so.3 (symbolic link to the above)
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/emul/linux/usr/X11/lib/libX11.so.3.1.0
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/emul/linux/usr/X11/lib/libX11.so.3 (symbolic link to the above)
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/emul/linux/lib/libc.so.4.6.29
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/emul/linux/lib/libc.so.4 (symbolic link to the above)
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.fi
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.Pp
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Note that if you already have a Linux shared library with a
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matching major revision number to the first column of the 'ldd'
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output, you won't need to copy the file named in the last column
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to your system, the one you already have should work. It is
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advisable to copy the shared library anyway if it is a newer version,
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though. You can remove the old one, as long as you make the symbolic
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link point to the new one. So, if you have these libraries
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on your system:
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.Pp
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.nf
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/emul/linux/lib/libc.so.4.6.27
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/emul/linux/lib/libc.so.4 -> /emul/linux/lib/libc.so.4.6.27
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.fi
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.Pp
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and you find that the ldd output for a new binary you want to
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install is:
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.nf
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.Pp
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libc.so.4 (DLL Jump 4.5pl26) => /lib/libc.so.4.6.29
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.fi
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.Pp
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you won't need to worry about copying /lib/libc.so.4.6.29 too,
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because the program should work fine with the slightly older version.
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You can decide to replace the libc.so anyway, and that should leave
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you with:
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.Pp
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.nf
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/emul/linux/lib/libc.so.4.6.29
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/emul/linux/lib/libc.so.4 -> /emul/linux/lib/libc.so.4.6.29
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.fi
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.Pp
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Please note that the symbolic link mechanism is
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.Em only
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needed for Linux binaries, the
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.Nx
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runtime linker takes care of
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looking for matching major revision numbers itself, you
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don't need to worry about that.
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.Pp
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Finally, you must make sure that you have the Linux runtime linker
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and its config files on your system. You should copy these
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files from the Linux system to their appropriate place on your
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.Nx
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system (in the /emul/linux tree):
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.Pp
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.nf
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/lib/ld.so
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/etc/ld.so.cache
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/etc/ld.so.config
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.fi
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.Pp
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.It 2.
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You don't have access to a Linux system. In that case, you
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should get the extra files you need from various ftp sites.
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Information on where to look for the various files is appended
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below. For now, let's assume you know where to get the files.
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.Pp
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Retrieve the following files (from _one_ ftp site to avoid
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any version mismatches), and install them under /emul/linux
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(i.e. /foo/bar is installed as /emul/linux/foo/bar):
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.Pp
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.nf
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/sbin/ldconfig
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/usr/bin/ldd
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/lib/libc.so.x.y.z
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/lib/ld.so
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.fi
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.Pp
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ldconfig and ldd don't necessarily need to be under /emul/linux,
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you can install them elsewhere in the system too. Just make sure
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they don't conflict with their
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.Nx
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counterparts. A good idea
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would be to install them in /usr/local/bin as ldconfig-linux and
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ldd-linux.
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.Pp
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Create the file /emul/linux/etc/ld.so.conf, containing the
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directories in which the Linux runtime linker should look
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for shared libs. It is a plain text file, containing a directory
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name on each line. /lib and /usr/lib are standard, you could
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add the following:
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.Pp
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.nf
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/usr/X11/lib
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/usr/local/lib
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.fi
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.Pp
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Note that these are mapped to /emul/linux/XXXX by
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.Nx Ns 's
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compat
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code, and should exist as such on your system.
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Run the Linux ldconfig program. It should be statically
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linked, so it doesn't need any shared libraries by itself.
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It will create the file /emul/linux/etc/ld.so.cache
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You should rerun the Linux version of the ldconfig program
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each time you add a new shared library.
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.Pp
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You should now be set up for Linux binaries which only need
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a shared libc. You can test this by running the Linux ldd
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on itself. Suppose that you have it installed as ldd-linux, it
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should produce something like:
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.Pp
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.Bl -tag -width 123 -compact -offset indent
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.It (me@netbsd) ldd-linux `which ldd-linux`
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libc.so.4 (DLL Jump 4.5pl26) => /lib/libc.so.4.6.29
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.El
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.Pp
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This being done, you are ready to install new Linux binaries.
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Whenever you install a new Linux program, you should check
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if it needs shared libraries, and if so, whether you have
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them installed in the /emul/linux tree. To do this, you run
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the Linux version ldd on the new program, and watch its output.
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ldd (see also the manual page for
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.Xr ldd 1 )
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will print a list
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of shared libraries that the program depends on, in the
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form <majorname> (<jumpversion>) => <fullname>.
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.Pp
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If it prints "not found" in stead of <fullname> it means that
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you need an extra library. Which library this is, is shown
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in <majorname>, which will be of the form libXXXX.so.<N>
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You will need to find a libXXXX.so.<N>.<mm> on a Linux ftp site,
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and install it on your system. The XXXX (name) and <N> (major
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revision number) should match; the minor number(s) <mm> are
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less important, though it is advised to take the most
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recent version.
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.El
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.Ss Setting up other files
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Newer version of Linux use /etc/nsswitch.conf for network information,
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such as YP and DNS. You must create or get a valid copy of this file
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and put it in /emul/linux/etc.
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.Ss Finding the necessary files.
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[
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.Em Note:
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As of April, 1997, a reasonable set of Linux libraries and other files
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needed for Linux emulation may be obtained from
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.Dl ftp://ftp.freebsd.org/pub/FreeBSD/distfiles/linux_lib-2.4.tar.gz
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It is recommended you try to retrieve this file (or a more recent
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version) from ftp.freebsd.org first as this tar file contains
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everything one typically needs and is is very simple to use for this
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application. Failing that, see the instructions below.
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]
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.Pp
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.Em Note:
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the information below is valid as of the time this
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document was written (March, 1995), but certain details
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such as names of ftp sites, directories and distribution names
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may have changed by the time you read this.
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.Pp
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Linux is distributed by several groups that make their own set
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of binaries that they distribute. Each distribution has its own
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name, like "Slackware" or "Yggdrasil". The distributions are
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available on a lot of ftp sites. Sometimes the files are unpacked,
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and you can get the individual files you need, but mostly they
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are stored in distribution sets, usually consisting of subdirectories
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with gzipped tar files in them. The primary ftp sites for the
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distributions are:
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.Pp
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.nf
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sunsite.unc.edu:/pub/Linux/distributions
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tsx-11.mit.edu:/pub/linux/distributions
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.fi
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.Pp
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Some European mirrors:
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.Pp
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.nf
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ftp.luth.se:/pub/linux/distributions
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ftp.demon.co.uk:/pub/linux/distributions
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src.doc.ic.ac.uk:/packages/linux/distributions
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.fi
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.Pp
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For simplicity, let's concentrate on Slackware here. This distribution
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consists of a number of subdirectories, containing separate packages.
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Normally, they're controlled by an install program, but you can
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retrieve files "by hand" too. First of all, you will need to look
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in the "contents" subdir of the distribution. You will find
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a lot of small textfiles here describing the contents of the seperate
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packages. The fastest way to look something up is to retrieve all
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the files in the contents subdirectory, and grep through them for the file
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you need. Here is an example of a list of files that you might need, and
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in which contents-file you will find it by grepping through them:
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.Pp
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.Bd -unfilled -offset indent
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Needed Package
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ld.so ldso
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ldconfig ldso
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ldd ldso
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libc.so.4 shlibs
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libX11.so.6.0 xf_lib
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libXt.so.6.0 xf_lib
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libX11.so.3 oldlibs
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libXt.so.3 oldlibs
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.Ed
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.Pp
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So, in this case, you will need the packages ldso, shlibs, xf_lib and oldlibs.
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In each of the contents-files for these packages, look for a line saying
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"PACKAGE LOCATION", it will tell you on which 'disk' the package is,
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in our case it will tell us in which subdirectory we need to look.
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For our example, we would find the following locations:
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.Pp
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.Bd -unfilled -offset indent
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Package Location
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ldso diska2
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shlibs diska2
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oldlibs diskx6
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xf_lib diskx9
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.Ed
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.Pp
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The locations called "diskXX" refer to the "slakware/XX" subdirectories
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of the distribution, others may be found in the "contrib" subdirectory.
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In this case, we could now retrieve the packages we need by retrieving
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the following files (relative to the root of the Slackware distribution
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tree):
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.Pp
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.nf
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slakware/a2/ldso.tgz
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slakware/a2/shlibs.tgz
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slakware/x6/oldlibs/tgz
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slakware/x9/xf_lib.tgz
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.fi
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.Pp
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Extract the files from these gzipped tarfiles in your /emul/linux directory
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(possibly omitting or afterwards removing files you don't need), and you
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are done.
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.Ss Programs using SVGAlib
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SVGAlib binaries require some extra care. The pcvt virtual console driver
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has to be in the kernel for them to work, and you will also have to create
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some symbloic links in the /emul/linux/dev directory, namely:
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.Pp
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.nf
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/emul/linux/dev/console -> /dev/tty
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/emul/linux/dev/mouse -> whatever device your mouse is connected to
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/emul/linux/dev/ttyS0 -> /dev/tty00
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/emul/linux/dev/ttyS1 -> /dev/tty01
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.fi
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.Pp
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Be warned: the first link mentioned here makes SVGAlib binaries
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work, but may confuse others, so you may have to remove it again at
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some point.
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.Sh BUGS
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The information about Linux distributions may become outdated.
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.Pp
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Pathnames pointed to by symbolic links are not looked up in the
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shadow root when running a Linux executable. This is not consistent.
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.Pp
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Linux executables can not handle directory offset cookies > 32 bits.
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Should such an offset occur, you will see the message "linux_getdents:
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dir offset too large for emulated program". Currently, this can only
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happen on NFS mounted filesystems, mounted from servers that return
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offsets with information in the upper 32 bits. These errors should
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rarely happen, but can be avoided by mounting this filesystem with offset
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translation enabled. See the
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.Fl X
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option to
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.Xr mount_nfs 8 .
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The
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.Fl 2
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option to
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.Xr mount_nfs 8
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will also have the desired effect, but is less preferable.
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