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diff --git a/share/examples/kld/cdev/README b/share/examples/kld/cdev/README new file mode 100644 index 000000000000..617a3460f86d --- /dev/null +++ b/share/examples/kld/cdev/README @@ -0,0 +1,130 @@ +# Copyright (c) 1998 Rajesh Vaidheeswarran +# All rights reserved. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions +# are met: +# 1. Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# 2. Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# 3. All advertising materials mentioning features or use of this software +# must display the following acknowledgement: +# This product includes software developed by Rajesh Vaidheeswarran +# 4. The name Rajesh Vaidheeswarran may not be used to endorse or promote +# products derived from this software without specific prior written +# permission. +# +# THIS SOFTWARE IS PROVIDED BY RAJESH VAIDHEESWARRAN ``AS IS'' AND ANY +# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +# ARE DISCLAIMED. IN NO EVENT SHALL THE RAJESH VAIDHEESWARRAN BE LIABLE +# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. +# +# Copyright (c) 1993 Terrence R. Lambert. +# All rights reserved. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions +# are met: +# 1. Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# 2. Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# 3. All advertising materials mentioning features or use of this software +# must display the following acknowledgement: +# This product includes software developed by Terrence R. Lambert. +# 4. The name Terrence R. Lambert may not be used to endorse or promote +# products derived from this software without specific prior written +# permission. +# +# THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``AS IS'' AND ANY +# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +# ARE DISCLAIMED. IN NO EVENT SHALL THE TERRENCE R. LAMBERT BE LIABLE +# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. +# +# + +1.0 Overview + + This is the README file for the sample kld module + that mimics a character device driver. + + A kld module may be used to load any data or + program into the kernel that can be made available by + modifying a table, pointer, or other kernel data to inform + the kernel that the module should be used instead of the + previous code/data path. + + Generally, it is assumed that a loadable module is one of + a set of similar modules (such as a file system or console + terminal emulation), and that the reference is through a + table (such as vfssw[]), and that a "special" value is + assigned to the slots which are allowed to be replaced. + This is not enforced, so you may use the kld module + any way you see fit. + + As with the loadable system calls, it may be desirable to + allow the module loader to replace an *existing* entry to + try out changes to kernel code without rebuilding and + booting from the new kernel. + + The idea behind this example is to show some interaction + with the device driver. Therefore the flow of the code that + this driver is aimed at is as follows: + + open(2) -> ioctl(2) -> write(2) -> read(2) -> close(2). + + We will first open the device in the /dev/ directory; then + we will send an ioctl message to it using ioctl(2) call; + then write a small string via the write(2) call. This string + we write to the device will be stored in a static buffer, + and later will be accessible via the read(2) call. Finally, + we will close(2) our open()'d device so that we may no + longer make read or write calls on it. + +2.0 Directions + + To test the module, do the following: + + cd module + make load + + A load message (the copyright) will be printed on the console. + + cd ../test + make load + + The system call prints a message on the console when called. + This message will be printed when running "make load" in + the "test" subdirectory. + + +3.0 Recovering resources + + The module consumes memory when loaded; it can be freed up by + unloading it. To unload it, type the following from the directory + this file is in: + + cd module + make unload + + The miscellaneous module will be unloaded by name. + + +4.0 END OF DOCUMENT |