Annotation of wikisrc/guide/linux.mdwn, revision 1.2

1.1       jdf         1: # Linux emulation
                      2: 
1.2     ! jdf         3: The NetBSD port for i386, amd64, mac68k, macppc, and many others can execute a
        !             4: great number of native Linux programs, using the Linux emulation layer.
        !             5: Generally, when you think about emulation you imagine something slow and
        !             6: inefficient because, often, emulations must reproduce hardware instructions and
        !             7: even architectures (usually from old machines) in software. In the case of the
        !             8: Linux emulation, this is radically different: it is only a thin software layer,
        !             9: mostly for system calls which are already very similar between the two systems.
        !            10: The application code itself is processed at the full speed of your CPU, so you
        !            11: don't get a degraded performance with the Linux emulation and the feeling is
1.1       jdf        12: exactly the same as for native NetBSD applications.
                     13: 
1.2     ! jdf        14: This chapter explains how to configure the Linux emulation with an example: the
1.1       jdf        15: installation of the well known Acrobat Reader version 7 program.
                     16: 
                     17: ## Emulation setup
                     18: 
1.2     ! jdf        19: The installation of the Linux emulation is described in the
        !            20: [compat\_linux(8)](http://netbsd.gw.com/cgi-bin/man-cgi?compat_linux+8+NetBSD-5.0.1+i386)
1.1       jdf        21: man page; using the package system, only two steps are needed.
                     22: 
                     23:  1. Configuring the kernel.
                     24:  2. Installing the Linux libraries.
                     25:  3. Installing Linux applications like Acrobat Reader
                     26: 
                     27: ### Configuring the kernel
                     28: 
1.2     ! jdf        29: If you use a GENERIC kernel you don't need to do anything because Linux
1.1       jdf        30: compatibility is already enabled.
                     31: 
                     32: If you use a customized kernel, check that the following options are enabled:
                     33: 
                     34:     option COMPAT_LINUX
                     35:     option EXEC_ELF32
                     36: 
                     37: or the following options if you are going to use 64-bit ELF binaries:
                     38: 
                     39:     option COMPAT_LINUX
                     40:     option EXEC_ELF64
                     41: 
1.2     ! jdf        42: When you have compiled a kernel with the previous options, you can start
1.1       jdf        43: installing the necessary software.
                     44: 
                     45: ### Installing the Linux libraries
                     46: 
1.2     ! jdf        47: Usually, applications are linked against shared libraries, and for Linux
        !            48: applications, Linux shared libraries are needed. You can get the shared
        !            49: libraries from any Linux distribution, provided it's not too old, but the
        !            50: suggested method is to use the package system and install the libraries
        !            51: automatically (which uses SUSE libraries). When you install the libraries, the
1.1       jdf        52: following happens:
                     53: 
1.2     ! jdf        54:  * A *secondary root directory* is created which will be used for Linux
        !            55:    programs. This directory is `/emul/linux`. The Linux programs in emulation
        !            56:    mode will use this directory as their root directory and use files there. If
1.1       jdf        57:    a required file is not found, it will be searched with `/` as root directory.
                     58: 
1.2     ! jdf        59:    For example, if a Linux application opens `/etc/ld.so.conf`, it will first be
        !            60:    searched in `/emul/linux/etc/ld.so.conf`, and if not found there, in
1.1       jdf        61:    `/etc/ld.so.conf`.
                     62: 
1.2     ! jdf        63:  * The shared libraries for Linux are installed. Most applications are linked
        !            64:    dynamically and expect to find the necessary libraries on the system. For
        !            65:    example, for Acrobat Reader, if you go to the `/usr/pkgsrc/print/acroread7`
        !            66:    and give the `make depends` command, pkgsrc will fetch and install all
1.1       jdf        67:    dependencies for Acrobat Reader.
                     68: 
1.2     ! jdf        69: Both operations will be handled automatically by the package system, without the
        !            70: need of manual intervention from the user (we suppose that, by now, you have
        !            71: already begun to love the package system...). Note that this section describes
1.1       jdf        72: manual installation of the Linux libraries.
                     73: 
1.2     ! jdf        74: To install the libraries, a program must be installed that handles the RPM
        !            75: format: it is `rpm`, which will be used to extract the SUSE libraries. Execute
        !            76: `make` and `make install` in the `/usr/pkgsrc/misc/rpm/` directory to build
1.1       jdf        77: and install `rpm`.
                     78: 
1.2     ! jdf        79: Next the `suse121_base` package must be installed. The SUSE RPM files can be
        !            80: downloaded by the package system or, if you have a SUSE CD, you can copy them in
1.1       jdf        81: the `/usr/pkgsrc/distfiles/suse121` directory and then run `make` and
1.2     ! jdf        82: `make install` after going to the `/usr/pkgsrc/emulators/suse121_base`
1.1       jdf        83: directory.
                     84: 
1.2     ! jdf        85: With the same method install `suse121_compat` and `suse121_x11`. The final
1.1       jdf        86: configuration is:
                     87: 
                     88:     # pkg_info -a | grep suse
                     89:        suse_base-12.1nb3   Linux compatibility package
                     90:        suse_compat-12.1    Linux compatibility package with old shared libraries
                     91:        suse_x11-12.1       Linux compatibility package for X11
                     92: 
1.2     ! jdf        93: *Note*: Of course you can also install the packages binary. To do this, you
1.1       jdf        94: would either set the proper `PKG_PATH` and then
                     95: 
                     96:     # pkg_add rpm
                     97:     # pkg_add suse_base
                     98:     # pkg_add suse_compat
                     99:     # pkg_add suse_x11
                    100: 
                    101: Or, using `pkgin`:
                    102: 
                    103:     # pkgin install rpm suse_base suse_compat suse_x11
                    104: 
1.2     ! jdf       105: *Note*: You can also skip this step when you are installing a package from
        !           106: pkgsrc which requires Linux emulation! A good example for this is the package
        !           107: `www/opera`, which will automatically install the packages needed for emulating
1.1       jdf       108: the Linux version of the Opera browser.
                    109: 
                    110: ### Installing Acrobat Reader
                    111: 
1.2     ! jdf       112: Now everything is ready for the installation of the Acrobat Reader program (or
        !           113: other Linux programs). Change to `/usr/pkgsrc/print/acroread7` and give the
1.1       jdf       114: usual commands.
                    115: 
                    116:     # make
                    117:     # make install
                    118: 
                    119: ### Note
                    120: 
1.2     ! jdf       121: To download and install Acrobat Reader you need to add the line
        !           122: `ACCEPTABLE_LICENSES+=adobe-acrobat-license` to `/etc/mk.conf` to accept the
1.1       jdf       123: Acrobat Reader license, simply follow the instructions given after `make`.
                    124: 
                    125: ## Directory structure
                    126: 
1.2     ! jdf       127: If we examine the outcome of the installation of the Linux libraries and
        !           128: programs we find that `/emul/linux` is a symbolic link pointing to
1.1       jdf       129: `/usr/pkg/emul/linux`, where the following directories have been created:
                    130: 
                    131:  * `bin/`
                    132:  * `dev/`
                    133:  * `etc/`
                    134:  * `lib/`
                    135:  * `opt/`
                    136:  * `proc/`
                    137:  * `root/`
                    138:  * `sbin/`
                    139:  * `usr/`
                    140:  * `var/`
                    141: 
1.2     ! jdf       142: *Note*: Please always refer to `/emul/linux` and not to `/usr/pkg/emul/linux`.
1.1       jdf       143: The latter is an implementation detail and may change in the future.
                    144: 
1.2     ! jdf       145: How much space is required for the Linux emulation software? On one system we
1.1       jdf       146: got the following figure:
                    147: 
                    148:     # cd /usr/pkg/emul
                    149:     # du -k /emul/linux/
                    150:     ...
                    151:     127804  /emul/linux/
                    152: 
1.2     ! jdf       153: Acrobat Reader, the program, has been installed in the usual directory for
1.1       jdf       154: package binaries: `/usr/pkg/bin`. It can be run just as any other program:
                    155: 
1.2     ! jdf       156:     $ acroread netbsd.pdf
1.1       jdf       157: 
                    158: ## Emulating /proc
                    159: 
1.2     ! jdf       160: Some Linux programs rely on a Linux-like `/proc` filesystem. The NetBSD procfs
        !           161: filesystem can emulate a `/proc` filesystem that contains Linux-specific
        !           162: pseudo-files. To accomplish this you can mount the procfs with the
1.1       jdf       163: `linux`-option:
                    164: 
                    165:     # mount_procfs -o linux procfs /emul/linux/proc
                    166: 
1.2     ! jdf       167: In this example a Linux-like proc filesystem will be mounted to the
        !           168: `/emul/linux/proc` directory. You can also let NetBSD mount it automatically
        !           169: during the booting process of NetBSD, by adding the following line to
1.1       jdf       170: `/etc/fstab`:
                    171: 
                    172:     procfs /emul/linux/proc procfs ro,linux
                    173: 
                    174: ## Using Linux browser plugins
                    175: 
1.2     ! jdf       176: Linux plugins for Mozilla-based browsers can be used on native NetBSD Firefox
        !           177: builds through nspluginwrapper, a wrapper that translates between the native
        !           178: browser and a foreign plugin. At the moment, nspluginwrapper only works reliably
        !           179: on Mozilla-based browsers that link against GTK2+ (GTK1+ is not supported).
1.1       jdf       180: nspluginwrapper can be installed through pkgsrc:
                    181: 
                    182:     # cd /usr/pkgsrc/www/nspluginwrapper
                    183:     # make install
                    184: 
1.2     ! jdf       185: Plugins can then be installed in two steps: first, the plugin has to be
        !           186: installed on the system (e.g. through pkgsrc). After that the plugin should be
        !           187: registered with the `nspluginwrapper` by the users who want to use that
1.1       jdf       188: plugin.
                    189: 
1.2     ! jdf       190: In this short example we will have a look at installing the Macromedia Flash
        !           191: plugin. We can fullfill the first step by installing the Flash plugin through
1.1       jdf       192: pkgsrc:
                    193: 
                    194:     # cd /usr/pkgsrc/multimedia/ns-flash
                    195:     # make install
                    196: 
                    197: After that an unprivileged user can register the Flash plugin:
                    198: 
                    199:     $ nspluginwrapper -i /usr/pkg/lib/netscape/plugins/libflashplayer.so
                    200: 
1.2     ! jdf       201: The plugin should then be registered correctly. You can check this by using the
        !           202: `-l` option of `nspluginwrapper` (`nspluginwrapper -l`). If the plugin is
        !           203: listed, you can restart Firefox, and verify that the plugin was installed by
1.1       jdf       204: entering `about:plugins` in the location bar.
                    205: 
                    206: ## Further reading
                    207: 
                    208: The following articles may be of interest for further understanding Linux (and other) emulation:
                    209: 
                    210:  * *[Implementing Linux emulation on NetBSD](http://www.linux.com/articles/35998)*. Peter Seebach. May 2004.
                    211:  * *[Linux compatibility on BSD for the PPC platform, part 1](http://www.onlamp.com/pub/a/onlamp/2001/05/10/linux_bsd.html)*. Emmanuel Dreyfus. May 2001.
                    212:  * *[Linux compatibility on BSD for the PPC platform, part 2](http://www.onlamp.com/pub/a/onlamp/2001/05/17/linux_bsd.html)*. Emmanuel Dreyfus. May 2001.
                    213:  * *[Linux compatibility on BSD for the PPC platform, part 3](http://www.onlamp.com/pub/a/onlamp/2001/06/07/linux_bsd.html)*. Emmanuel Dreyfus. Jun 2001.
                    214:  * *[Linux compatibility on BSD for the PPC platform, part 4](http://www.onlamp.com/pub/a/onlamp/2001/06/21/linux_bsd.html)*. Emmanuel Dreyfus. Jun 2001.
                    215:  * *[Linux compatibility on BSD for the PPC platform, part 5](http://www.onlamp.com/pub/a/onlamp/2001/08/09/linux_bsd.html)*. Emmanuel Dreyfus. Aug 2002.
                    216:  * *[Irix binary compatibility, part 1](http://www.onlamp.com/pub/a/bsd/2002/08/08/irix.html)*. Emmanuel Dreyfus. Aug 2002.
                    217:  * *[Irix binary compatibility, part 2](http://www.onlamp.com/pub/a/bsd/2002/08/29/irix.html)*. Emmanuel Dreyfus. Aug 2002.
                    218:  * *[Irix binary compatibility, part 3](http://www.onlamp.com/pub/a/bsd/2002/09/12/irix.html)*. Emmanuel Dreyfus. Sep 2002.
                    219:  * *[Irix binary compatibility, part 4](http://www.onlamp.com/pub/a/bsd/2002/10/10/irix.html)*. Emmanuel Dreyfus. Oct 2002.
                    220:  * *[Irix binary compatibility, part 5](http://www.onlamp.com/pub/a/bsd/2002/12/19/irix.html)*. Emmanuel Dreyfus. Dec 2002.
                    221:  * *[Irix binary compatibility, part 6](http://www.onlamp.com/pub/a/bsd/2003/04/03/irix.html)*. Emmanuel Dreyfus. Apr 2003.
                    222: 

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