patch-pre2.0.14-final2.0 linux/Documentation/modules.txt

• Lines: 210
• Date: Fri Jun 7 16:28:46 1996
• Orig file: pre2.0.14/linux/Documentation/modules.txt
• Orig date: Thu Jun 6 17:42:32 1996

diff -u --recursive --new-file pre2.0.14/linux/Documentation/modules.txt linux/Documentation/modules.txt
@@ -3,10 +3,6 @@
 the internals of module, but mostly a sample of how to compile
 and use modules.
 
-In this kernel you also have a possibility to create modules that are
-less dependent on the kernel version.  This option can be selected
-during "make config", by enabling CONFIG_MODVERSIONS.
-
 Note: You should ensure that the modules-X.Y.Z.tar.gz you are using
 is the most up to date one for this kernel. The "X.Y.Z" will reflect
 the kernel version at the time of the release of the modules package.
@@ -16,16 +12,21 @@
 package is by looking up the URL listed for "Bjorn Ekwall" in the 
 file ./linux/CREDITS)
 
+
+In the beginning...
+-------------------
+
 Anyway, your first step is to compile the kernel, as explained in the
-file README.  It generally goes like:
+file linux/README.  It generally goes like:
 
 	make config
 	make dep
 	make clean
 	make zImage or make zlilo
 
-In "make config", you select what you want to include in the kernel.
-You will generally select the minimal set that is needed to boot:
+In "make config", you select what you want to include in the "resident"
+kernel and what features you want to have available as loadable modules.
+You will generally select the minimal resident set that is needed to boot:
 
 	The filesystem of your root partition
 	A scsi driver, but see below for a list of SCSI modules!
@@ -35,8 +36,18 @@
 
 	plus those things that you just can't live without...
 
-What has been left out is generally loadable as a modules.
-The set of modules is rapidly increasing, but so far these are known:
+The set of modules is constantly increasing, and you will be able to select
+the option "m" in "make config" for those features that the current kernel
+can offer as loadable modules.
+
+You also have a possibility to create modules that are less dependent on
+the kernel version.  This option can be selected during "make config", by
+enabling CONFIG_MODVERSIONS, and is most useful on "stable" kernel versions,
+such as the kernels from the 1.2 and 2.0 series.
+If you have modules that are based on sources that are not included in
+the official kernel sources, you will certainly like this option...
+
+Here is a sample of the available modules included in the kernel sources:
 
 	Most filesystems: minix, xiafs, msdos, umsdos, sysv, isofs, hpfs,
 			  smbfs, nfs
@@ -59,25 +70,21 @@
 		           Longshine LCS-7260, TEAC CD-55A
 		sonycd535: Sony CDU-531/535, CDU-510/515
 
-	Some misc modules:
+	And a lot of misc modules, such as:
 		lp: line printer
 		binfmt_elf: elf loader
 		binfmt_java: java loader
 		isp16: cdrom interface
+		serial: the serial (tty) interface
 
 When you have made the kernel, you create the modules by doing:
 
 	make modules
 
-This will compile all modules and update the modules directory.
+This will compile all modules and update the linux/modules directory.
 In this directory you will then find a bunch of symbolic links,
 pointing to the various object files in the kernel tree.
-
-As soon as you have rebooted the newly made kernel, you can install
-and remove modules at will with the utilities: "insmod" and "rmmod".
-
-
-Now, after you have made all modules, you can also do:
+Now, after you have created all your modules, you should also do:
 
 	make modules_install
 
@@ -85,17 +92,36 @@
 "/lib/modules/kernel_release/", where "kernel_release" is something
 like 2.0.1, or whatever the current kernel version is...
 
+As soon as you have rebooted the newly made kernel, you can install
+and remove modules at will with the utilities: "insmod" and "rmmod".
+After reading the man-page for insmod, you will also know how easy
+it is to configure a module when you do "insmod" (hint: symbol=value).
+
 
 Nifty features:
+---------------
+
+You also have access to two utilities: "modprobe" and "depmod", where
+modprobe is a "wrapper" for (or extension to) "insmod".
+These utilities use (and maintain) a set of files that describe all the
+modules that are available for the current kernel in the /lib/modules
+hierarchy as well as their interdependencies.
 
-You have access to two utilities: "modprobe" and "depmod".
 Using the modprobe utility, you can load any module like this:
 
 	/sbin/modprobe module
 
-without paying much attention to which kernel you are running.
+without paying much attention to which kernel you are running, or what
+other modules this module depends on.
+
+With the help of the modprobe configuration file: "/etc/conf.modules"
+you can tune the behaviour of modprobe in many ways, including an
+automatic setting of insmod options for each module.
+And, yes, there _are_ man-pages for all this...
+
 To use modprobe successfully, you generally place the following
-command in your /etc/rc.d/rc.S script.
+command in your /etc/rc.d/rc.S script.  (Read more about this in the
+"rc.hints" file in the module utilities package, "modules-x.y.z.tar.gz".)
 
 	/sbin/depmod -a
 
@@ -106,6 +132,82 @@
 
 you will automatically load _both_ the msdos and umsdos modules,
 since umsdos runs piggyback on msdos.
+
+
+The "ultimate" utility:
+-----------------------
+
+OK, you have read all of the above, and feel amply impressed...
+Now, we tell you to forget all about how to install and remove
+loadable modules...
+With the kerneld daemon, all of these chores will be taken care of
+automatically.  Just answer "Y" to CONFIG_KERNELD in "make config",
+and make sure that /sbin/kerneld is started as soon as possible
+after boot and that "/sbin/depmod -a" has been executed for the
+current kernel. (Read more about this in the module utilities package.)
+
+Whenever a program wants the kernel to use a feature that is only
+available as a loadable module, and if the kernel hasn't got the
+module installed yet, the kernel will ask the kerneld deamon to take
+care of the situation and make the best of it.
+
+This is what happens:
+
+	- The kernel notices that a feature is requested that is not
+	  resident in the kernel.
+	- The kernel sends a message to kerneld, with a symbolic
+	  description of the requested feature.
+	- The kerneld daemon asks e.g. modprobe to load a module that
+	  fits this symbolic description.
+	- modprobe looks into its internal "alias" translation table
+	  to see if there is a match.  This table can be reconfigured
+	  and expanded by having "alias" lines in "/etc/conf.modules".
+	- insmod is then asked to insert the module(s) that modprobe
+	  has decided that the kernel needs.  Every module will be
+	  configured according to the "options" lines in "/etc/conf.modules".
+	- modprobe exits and kerneld tells the kernel that the request
+	  succeded (or failed...)
+	- The kernel uses the freshly installed feature just as if it
+	  had been configured into the kernel as a "resident" part.
+
+The icing of the cake is that when an automatically installed module
+has been unused for a period of time (usually 1 minute), the module
+will be automatically removed from the kernel as well.
+
+This makes the kernel use the minimal amount of memory at any given time,
+making it available for more productive use than as just a placeholder for
+unused code.
+
+Actually, this is only a side-effect from the _real_ benefit of kerneld:
+You only have to create a minimal kernel, that is more or less independent
+of the actual hardware setup.  The setup of the "virtual" kernel is
+instead controlled by a configuration file as well as the actual usage
+pattern of the current machine and its kernel.
+This should be good news for maintainers of multiple machines as well as
+for maintainers of distributions.
+
+To use kerneld with the least amount of "hassle", you need modprobe from
+a release that can be considered "recent" w.r.t. your kernel, and also
+a configuration file for modprobe ("/etc/conf.modules").
+Since modprobe already knows about most modules, the minimal configuration
+file could look something like this:
+
+	alias scsi_hostadapter aha1542  # or whatever SCSI adapter you have
+	alias eth0 3c509	# or whatever net adapter you have
+	# you might need an "options" line for some net adapters:
+	options 3c509 io=0x300 irq=10
+	# you might also need an "options" line for some other module:
+	options cdu31a cdu31a_port=0x1f88 sony_pas_init=1
+
+You could add these lines as well, but they are only "cosmetic":
+
+	alias net-pf-3 off	# no ax25 module available (yet)
+	alias net-pf-4 off	# if you don't use the ipx module
+	alias net-pf-5 off	# if you don't use the appletalk module
+
+Finally, for the "purists":
+You can name the modprobe configuration either "/etc/conf.modules" or
+"/etc/modules.conf", since modprobe knows what to do in each case...
 
 
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