FreeBSD/Linux Kernel Cross Reference
sys/boot/

	Name	Size	Last modified (GMT)	Description
	Parent directory		2009-04-23 21:24:58
	common/		2009-04-23 21:24:23
	efi/		2009-02-08 18:52:42
	ficl/		2009-04-23 21:24:23
	forth/		2009-04-23 21:24:23
	ia64/		2009-02-08 18:52:42
	ofw/		2009-02-08 18:52:42
	pc32/		2009-04-23 21:24:23
	powerpc/		2009-02-08 18:52:43
	sparc64/		2009-02-08 18:52:43
	Makefile	699 bytes	2009-02-08 18:52:42
	README	11613 bytes	2009-02-08 18:52:42

     $FreeBSD: src/sys/boot/README,v 1.3 2000/05/01 20:26:17 peter Exp $
     $DragonFly: src/sys/boot/README,v 1.4 2005/02/26 12:00:55 swildner Exp $
     
            README file, for the boot config file setup.  This is meant
            to explain how to manage the loader configuration process.
            The boot and loading process is either defined, or being
            defined in boot(8) and loader(8).
     
            The ongoing development of the FreeBSD bootloader, and its
           rapid deployment while still in the development phase, has
           resulted in a large number of installations with outdated
           configurations.  Those installations actively tracking the
           FreeBSD development should also ensure that their bootloader
           configurations are updated.  If you see files discussed here
           that your system doesn't yet have, add them yourself.
    
           This is an effort to give the currently correct method for
           setting up your boot process.  It includes information on
           setting up screen savers and plug and play information, and
           also on recording any changes you make in your kernel
           configuration.  This file is temporary, because as I noted,
           the process is still undergoing development, and will still
           change.  Man pages are coming out, but they're still going
           to be somewhat fragile for a while.  If you note anything in
           here that's broken, it would be a good idea to report it to
           the FreeBSD-current list, or to Daniel C. Sobral
           <dcs@FreeBSD.org> or Mike Smith <msmith@FreeBSD.org>.
    
           NOTE:
    
           Please understand, all this is very current development, and
           while getting this working for STABLE is a goal, it's not
           yet ready for that.  It's possible that parts of this might
           indeed work for stable, but if you're not absolutely sure
           what you're doing, you're better off not using the
           information in this README for STABLE.  Use this for current
           only for a while longer, please!
    
           After the first two stages in the booting process (described
           in boot(8)), the last stage of the booting process, called
           the loader (see loader(8)) reads in the /boot/loader.rc
           file.  The two lines you should have there are:
    
           include /boot/loader.4th
           start
    
           This reads the ficl (forth) initialization files, then
           /boot/default/loader.conf.  This file, which strongly
           resembles in form /etc/rc.conf but functions quite
           differently, has spots for endless user customization but
           isn't yet completely finished.  For one thing, it used to
           assume a /kernel.config instead of a /boot/kernel.conf.
           Watch the first few lines of /boot/defaults/loader.conf to
           see if the file name changes.
    
           [See the section at the end on loader.conf syntax]
    
           You don't actually want to make any changes to
           /boot/defaults/loader.conf, the file that is a  hacking-
           target is:
    
           /boot/loader.conf
    
           and might very likely not exist yet on your system).  You
           should copy /boot/defaults/loader.conf to /boot/loader.conf,
           and then cut out anything you didn't want changed.
    
           The start command also loads your kernel for you, so don't
           put any lines in there like "load kernel", they'll fail (but
           really have already worked for you).  Start also reads in
           the file /boot/defaults/loader.conf and /boot/loader.conf.
           If you don't have /boot/loader.conf, you'll see a message on
           boot about it, but it's a warning only, no other effects.
           See the section on loader.conf syntax at the end of this
           document, for some more pointers on loader.conf syntax.
    
           The best way to manage splash screens is with entries in
           /boot/loader.conf, and this is very clearly illustrated in
           /boot/defaults/loader.conf (which you could just copy over
           to /boot/loader.conf).  I'm going to illustrate here how you
           *could* do it in /boot/loader.rc (for information only)
           but I don't recommend you do this; use the
           /boot/defaults/loader.conf syntax, it's easier to get it
           correct.
    
           You can load your splash screen by putting the following
           lines into /boot/loader.rc:
    
           load splash_bmp
           load -t splash_image_data /path/to/file.bmp
    
           The top line causes the splash_bmp module to get loaded.
           The second line has the parameter "-t" which tells the
           loader that the class of DATA being loaded is not a module,
           but instead a splash_image_data located in file
           /path/to/file.bmp.
    
           To get your plug and play data correctly set, run kget,
           redirecting the output to /boot/kernel.conf.  Note that kget
          right now adds an extra "q" to it's output (from the q for
          quit you press when you exit config), and if you want, you
          can remove that from the file.  Kget reports data only, so
          feel free to run it, just to see the output.  Make certain
          you have the kernel option USERCONFIG set in your kernel, so
          that you can do a boot -c, to initially set your cards up.
          Then, edit /boot/loader.conf so that the following line
          shows up (overwriting, in effect, a similar line in
          /boot/default/loader.conf):
   
          userconfig_script_load="YES"
   
          My own pnp line looks like:
          pnp 1 0 os irq0 15 irq1 0 drq0 1 drq1 0 port0 1332
          (kget changes numbers from hexadecimal to decimal).  Note
          that, at this moment, the change from using /kernel.config
          to using /boot/kernel.conf as the storage place for kernel
          config changes is going on.  Take a look at your
          /boot/defaults/loader.conf, see what's defined as
          userconfig_script_name, and if you override, make sure the
          file exists.  Note that the loader only has access to the
          root filesystem, so be careful where you tell it to read
          from.
   
   
             o If you interrupt autoboot, you'll engage interactive
               mode with loader. Everything you type will have the
               same effects as if it were lines in /boot/loader.rc.
   
             o While in interactive mode, you can get help by typing
               "?", "help [<topic> [<subtopic>]]" and "help index".
               These are mostly commands one would expect a normal
               user to use. I recommend you play with them a little,
               to gain further familiarity with what's going on.
   
               Note that it is not possible to damage or corrupt your
               system while experimenting with the loader, as it
               cannot write to any of your filesystems.
   
             o The command "unload" will unload everything. This is
               very useful.  Once loader.rc has finished and the
               system is in the autoboot count-down, you will usually
               have the kernel and other modules loaded. Now, suppose
               your new /kernel is broken, how do you load
               /kernel.old? By typing:
   
                    unload
                    load kernel.old
                    [any other modules you wish to load]
                    boot
   
             o If you use loader.conf, you can do:
   
                    unload
                    set kernel=kernel.old
                    boot-conf
   
               this will then load all the modules you have
               configured, using kernel.old as kernel, and boot.
   
             o From loader, you can use the command "more" to read the
               contents of /boot/loader.rc, if you wish. This is not
               FreeBSD's more. It is one of loader's builtin commands.
               Useful if you can't quite recall what you have there.
               :-) Of course, you can use this command to read
               anything else you want.
   
             o "boot -flag" works, "boot kernelname" works, "boot
               -flag kernelname" doesn't. "boot kernelname -flag"
               might work, but I'm not sure. The problem is that these
               flags are kernel's flags, not boot's flags.
   
             o There are a number of variables that can be set. You
               can see them in loader.conf, but you can get much more
               detailed information using the "help" command, eg. help
               set <variablename>.
   
             o The variable root_disk_unit is particularly important,
               as it solves a relatively common problem. This problem
               shows when the BIOS assign disk units in a different
               way than the kernel. For example, if you have two IDE
               disks, one on the primary, the other on the secondary
               controller, and both as master, the default in most
               kernels is having the first as ad0, and the second as
               ad2. If your root partition is in ad2, you'll get an
               error, because the BIOS sees these disks as 0 and 1
               (well, 1 and 2), and that's what loader tells the
               kernel. In this case, "set root_disk_unit=2" solves the
               problem.  You use this whenever the kernel fails to
               mount to root partition because it has a wrong unit
               number.
   
          FILE OVERVIEW
   
   
             o /boot/defaults/loader.conf -- Master configuration
               file, not to be edited.  Overridden by
               /boot/loader.conf.
   
             o /boot/loader.conf -- local system customization file,
               in form very much like /boot/defaults/loader.conf.
               This file is meant to be used by local users and the
               sysinstall process.
   
             o /boot/loader.conf.local -- local installation override
               file.  This is intended for use by installations with
               large numbers of systems, to allow global policy
               overrides.  No FreeBSD tools should ever write this
               file.
   
             o /kernel.config -- old location of kernel configuration
               changes (like pnp changes).
   
             o /boot/kernel.conf -- new location for kernel
               configuration changes.
   
             o /boot/loader.rc -- loader initial configuration file,
               chiefly used to source in a forth file, and start the
               configuration process.
   
          NOTES ON LOADER.CONF SYNTAX
   
          I'm copy here from the last 11 lines from
          /boot/defaults/loader.conf:
   
          ##############################################################
          ###  Module loading syntax example  ##########################
          ##############################################################
   
          #module_load="YES"              # loads module "module"
          #module_name="realname"         # uses "realname" instead of "module"
          #module_type="type"             # passes "-t type" to load
          #module_flags="flags"           # passes "flags" to the module
          #module_before="cmd"            # executes "cmd" before loading module
          #module_after="cmd"             # executes "cmd" after loading module
          #module_error="cmd"             # executes "cmd" if load fails
   
          The way this works, the command processor used by the loader
          (which is a subset of forth) inspects  these  variables  for
          their  suffix,  and  the  7  lines  above illustrate all the
          currently defined suffixes, and their use.   Take  the  part
          before  the  underscore,  and customize it i(make it unique)
          for your particular use, keeping the  suffix  to  allow  the
          particular function you want to activate.  Extra underscores
          are fine, because it's only the  sufixes  that  are  scanned
          for.
   
   
   
          (authors Chuck Robey and Daniel Sobral).