eb2cd84505
informaltable element properly, unless the pgwide attribute is explicitly set to 1. Use this consistently within the (en) tree, and update the FDP accordingly. This should finally silence the demons in: PR: docs/73095 Submitted by: Hilko Meyer <Hilko dot Meyer at gmx dot de>
635 lines
29 KiB
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635 lines
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<!-- Copyright (c) 2001 The FreeBSD Documentation Project
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Redistribution and use in source (SGML DocBook) and 'compiled' forms
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(SGML, HTML, PDF, PostScript, RTF and so forth) with or without
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modification, are permitted provided that the following conditions
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1. Redistributions of source code (SGML DocBook) must retain the above
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copyright notice, this list of conditions and the following
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disclaimer as the first lines of this file unmodified.
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2. Redistributions in compiled form (transformed to other DTDs,
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converted to PDF, PostScript, RTF and other formats) must reproduce
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the above copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other materials
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provided with the distribution.
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THIS DOCUMENTATION IS PROVIDED BY THE FREEBSD DOCUMENTATION PROJECT "AS
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IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NIK CLAYTON BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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ANY WAY OUT OF THE USE OF THIS DOCUMENTATION, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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$FreeBSD$
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-->
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<!DOCTYPE article PUBLIC "-//FreeBSD//DTD DocBook V4.1-Based Extension//EN" [
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<!ENTITY % articles.ent PUBLIC "-//FreeBSD//ENTITIES DocBook FreeBSD Articles Entity Set//EN">
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%articles.ent;
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<!ENTITY legalnotice SYSTEM "../../share/sgml/legalnotice.sgml">
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]>
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<article>
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<articleinfo>
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<title>FreeBSD and Solid State Devices</title>
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<authorgroup>
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<author>
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<firstname>John</firstname>
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<surname>Kozubik</surname>
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<affiliation>
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<address><email>john@kozubik.com</email></address>
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</affiliation>
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</author>
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</authorgroup>
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<pubdate>$FreeBSD$</pubdate>
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<copyright>
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<year>2001</year>
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<holder>The FreeBSD Documentation Project</holder>
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</copyright>
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<legalnotice id="trademarks" role="trademarks">
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&tm-attrib.freebsd;
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&tm-attrib.m-systems;
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&tm-attrib.general;
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</legalnotice>
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&legalnotice;
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<abstract>
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<para>This article covers the use of solid state disk devices in FreeBSD
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to create embedded systems.</para>
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<para>Embedded systems have the advantage of increased stability due to
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the lack of integral moving parts (hard drives). Account must be
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taken, however, for the generally low disk space available in the
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system and the durability of the storage medium.</para>
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<para>Specific topics to be covered include the types and attributes of
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solid state media suitable for disk use in FreeBSD, kernel options
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that are of interest in such an environment, the
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<filename>rc.diskless</filename> mechanisms that automate the
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initialization of such systems and the need for read-only filesystems,
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and building filesystems from scratch. The article will conclude
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with some general strategies for small and read-only FreeBSD
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environments.</para>
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</abstract>
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</articleinfo>
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<sect1 id="intro">
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<title>Solid State Disk Devices</title>
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<para>The scope of this article will be limited to solid state disk
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devices made from flash memory. Flash memory is a solid state memory
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(no moving parts) that is non-volatile (the memory maintains data even
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after all power sources have been disconnected). Flash memory can
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withstand tremendous physical shock and is reasonably fast (the flash
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memory solutions covered in this article are slightly slower than a EIDE
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hard disk for write operations, and much faster for read operations).
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One very important aspect of flash memory, the ramifications of which
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will be discussed later in this article, is that each sector has a
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limited rewrite capacity. You can only write, erase, and write again to
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a sector of flash memory a certain number of times before the sector
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becomes permanently unusable. Although many flash memory products
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automatically map bad blocks, and although some even distribute write
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operations evenly throughout the unit, the fact remains that there
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exists a limit to the amount of writing that can be done to the device.
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Competitive units have between 1,000,000 and 10,000,000 writes per
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sector in their specification. This figure varies due to the
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temperature of the environment.</para>
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<para>Specifically, we will be discussing ATA compatible compact-flash
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units and the M-Systems &diskonchip; flash memory unit. ATA compatible
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compact-flash cards are quite popular as storage media for digital
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cameras. Of particular interest is the fact that they pin out directly
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to the IDE bus and are compatible with the ATA command set. Therefore,
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with a very simple and low-cost adaptor, these devices can be attached
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directly to an IDE bus in a computer. Once implemented in this manner,
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operating systems such as FreeBSD see the device as a normal hard disk
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(albeit small). The M-Systems &diskonchip; product is based on the same
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underlying flash memory technology as ATA compatible compact-flash
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cards, but resides in a DIP form factor and is not ATA compatible. To
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use such a device, not only must you install it on a motherboard that
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has a &diskonchip; socket, you must also build the `fla` driver into any
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FreeBSD kernel you wish to use it with. Further, there is critical,
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manufacturer-specific data residing in the boot sector of this device,
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so you must take care not to install the FreeBSD (or any other) boot
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loader when using this.</para>
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<para>Other solid state disk solutions do exist, but their expense,
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obscurity, and relative unease of use places them beyond the scope of
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this article.</para>
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</sect1>
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<sect1 id="kernel">
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<title>Kernel Options</title>
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<para>A few kernel options are of specific interest to those creating
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an embedded FreeBSD system.</para>
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<para>First, all embedded FreeBSD systems that use flash memory as system
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disk will be interested in memory disks and memory filesystems. Because
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of the limited number of writes that can be done to flash memory, the
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disk and the filesystems on the disk will most likely be mounted
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read-only. In this environment, filesystems such as
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<filename>/tmp</filename> and <filename>/var</filename> are mounted as
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memory filesystems to allow the system to create logs and update
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counters and temporary files. Memory filesystems are a critical
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component to a successful solid state FreeBSD implementation.</para>
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<para>You should make sure the following lines exist in your kernel
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configuration file:</para>
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<programlisting>options MFS # Memory Filesystem
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options MD_ROOT # md device usable as a potential root device
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pseudo-device md # memory disk</programlisting>
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<para>Second, if you will be using the M-Systems &diskonchip; product, you
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must also include this line:</para>
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<programlisting>device fla0 at isa?</programlisting>
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</sect1>
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<sect1 id="ro-fs">
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<title><filename>rc.diskless</filename> and Read-Only Filesystems</title>
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<para>The post-boot initialization of an embedded FreeBSD system is
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controlled by <filename>/etc/rc.diskless2</filename>
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(<filename>/etc/rc.diskless1</filename> is for BOOTP diskless boot).
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This initialization script is invoked by placing a line in
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<filename>/etc/rc.conf</filename> as follows:</para>
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<programlisting>diskless_mount=/etc/rc.diskless2</programlisting>
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<para><filename>rc.diskless2</filename> mounts <filename>/var</filename>
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as a memory filesystem, makes a configurable list of directories in
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<filename>/var</filename> with the &man.mkdir.1; command, changes modes
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on some of those directories, and extracts a list of device entries to
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copy to a writable (again, a memory filesystem)
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<filename>/dev</filename> partition. In the execution of
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<filename>/etc/rc.diskless2</filename>, one other
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<filename>rc.conf</filename> variable comes into play -
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<literal>varsize</literal>. The <filename>/etc/rc.diskless2</filename>
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file creates a <filename>/var</filename> partition based on the value of
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this variable in <filename>rc.conf</filename>:</para>
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<programlisting>varsize=8192</programlisting>
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<para>Remember that this value is in sectors. The creation of the
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<filename>/dev</filename> partition by
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<filename>/etc/rc.diskless2</filename>, however, is governed by a
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hard-coded value of 4096 sectors. It is trivial to change this entry in
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the <filename>/etc/rc.diskless2</filename> file itself, although you
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should not need more space than that for
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<filename>/dev</filename>.</para>
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<para>It is important to remember that the
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<filename>/etc/rc.diskless2</filename> script assumes that you have
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already removed your conventional <filename>/tmp</filename> partition
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and replaced it with a symbolic link to <filename>/var/tmp</filename>.
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Because <filename>tmp</filename> is one of the directories created in
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<filename>/var</filename> by the <filename>/etc/rc.diskless2</filename>
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script, and because <filename>/var</filename> is a memory filesystem
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(which is mounted read-write), <filename>/tmp</filename> will now be a
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directory that is read-write as well.</para>
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<para>The fact that <filename>/var</filename> and
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<filename>/dev</filename> are read-write filesystems is an important
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distinction, as the <filename>/</filename> partition (and any other
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partitions you may have on your flash media) should be mounted
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read-only. Remember that in <xref linkend="intro"> we detailed the
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limitations of flash memory - specifically the limited write capability.
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The importance of not mounting filesystems on flash media read-write,
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and the importance of not using a swap file, cannot be overstated. A
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swap file on a busy system can burn through a piece of flash media in
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less than one year. Heavy logging or temporary file creation and
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destruction can do the same. Therefore, in addition to removing the
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<literal>swap</literal> and <literal>/proc</literal> entries from your
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<filename>/etc/fstab</filename> file, you should also change the Options
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field for each filesystem to <literal>ro</literal> as follows:</para>
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<programlisting># Device Mountpoint FStype Options Dump Pass#
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/dev/ad0s1a / ufs ro 1 1</programlisting>
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<para>A few applications in the average system will immediately begin to
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fail as a result of this change. For instance, ports will not install
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from the ports tree because the
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<filename>/var/db/port.mkversion</filename> file does not exist. cron
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will not run properly as a result of missing cron tabs in the
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<filename>/var</filename> created by
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<filename>/etc/rc.diskless2</filename>, and syslog and dhcp will
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encounter problems as well as a result of the read-only filesystem and
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missing items in the <filename>/var</filename> that
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<filename>/etc/rc.diskless2</filename> has created. These are only
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temporary problems though, and are addressed, along with solutions to
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the execution of other common software packages in
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<xref linkend="strategies">.</para>
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<para>An important thing to remember is that a filesystem that was mounted
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read-only with <filename>/etc/fstab</filename> can be made read-write at
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any time by issuing the command:</para>
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<screen>&prompt.root; <userinput>/sbin/mount -uw <replaceable>partition</replaceable></userinput></screen>
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<para>and can be toggled back to read-only with the command:</para>
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<screen>&prompt.root; <userinput>/sbin/mount -ur <replaceable>partition</replaceable></userinput></screen>
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</sect1>
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<sect1>
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<title>Building a File System From Scratch</title>
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<para>Because ATA compatible compact-flash cards are seen by FreeBSD as
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normal IDE hard drives, as is a M-Systems &diskonchip; product (when you
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are running a kernel with the fla driver built in) you could
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theoretically install FreeBSD from the network using the kern and
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mfsroot floppies or from a CD. Other than the fact that you should not
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write a boot-loader of any kind to the M-Systems device, no special
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instructions are needed.</para>
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<para>However, even a small installation of FreeBSD using normal
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installation procedures can produce a system in size of greater than 200
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megabytes. Because most people will be using smaller flash memory
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devices (128 megabytes is considered fairly large - 32 or even 16
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megabytes is common) an installation using normal mechanisms is not
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possible—there is simply not enough disk space for even the
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smallest of conventional installations.</para>
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<para>The easiest way to overcome this space limitation is to install
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FreeBSD using conventional means to a normal hard disk. After the
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installation is complete, pare down the operating system to a size that
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will fit onto your flash media, then tar the entire filesystem. The
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following steps will guide you through the process of preparing a piece
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of flash memory for your tarred filesystem. Remember, because a normal
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installation is not being performed, operations such as partitioning,
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labeling, file-system creation, etc. need to be performed by hand. In
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addition to the kern and mfsroot floppy disks, you will also need to use
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the fixit floppy. If you are using a M-Systems &diskonchip;, the kernel
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on your kern floppy must have the <literal>fla</literal> option detailed
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in <xref linkend="kernel"> compiled into it. Please see
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<xref linkend="kern.flp"> for instructions on creating a new kernel for
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<filename>kern.flp</filename>.</para>
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<procedure>
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<step>
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<title>Partitioning your flash media device</title>
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<para>After booting with the kern and mfsroot floppies, choose
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<literal>custom</literal> from the installation menu. In the custom
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installation menu, choose <literal>partition</literal>. In the
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partition menu, you should delete all existing partitions using the
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<keycap>d</keycap> key. After deleting all existing partitions,
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create a partition using the <keycap>c</keycap> key and accept the
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default value for the size of the partition. When asked for the
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type of the partition, make sure the value is set to
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<literal>165</literal>. Now write this partition table to the disk
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by pressing the <keycap>w</keycap> key (this is a hidden option on
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this screen). When presented with a menu to choose a boot manager,
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take care to select <literal>None</literal> if you are using an
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M-Systems &diskonchip;. If you are using an ATA compatible compact
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flash card, you should choose the FreeBSD Boot Manager. Now press
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the <keycap>q</keycap> key to quit the partition menu. You will be
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shown the boot manager menu once more - repeat the choice you made
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earlier.</para>
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</step>
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<step>
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<title>Creating filesystems on your flash memory device</title>
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<para>Exit the custom installation menu, and from the main
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installation menu choose the <literal>fixit</literal> option. After
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entering the fixit environment, enter the following commands:</para>
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<informaltable frame="none" pgwide="1">
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<tgroup cols="2">
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<thead>
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<row>
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<entry align="center">ATA compatible</entry>
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<entry align="center">&diskonchip;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><para><screen>&prompt.root; <userinput>mknod /dev/ad0a c 116 0</userinput>
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&prompt.root; <userinput>mknod /dev/ad0c c 116 2</userinput>
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&prompt.root; <userinput>disklabel -e /dev/ad0c</userinput></screen></para></entry>
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<entry><para><screen>&prompt.root; <userinput>mknod /dev/fla0a c 102 0</userinput>
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&prompt.root; <userinput>mknod /dev/fla0c c 102 2</userinput>
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&prompt.root; <userinput>disklabel -e /dev/fla0c</userinput></screen></para></entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>At this point you will have entered the vi editor under the
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auspices of the disklabel command. If you are using &diskonchip;,
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the first step will be to change the type value near the beginning
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of the file from <literal>ESDI</literal> to
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<literal>DOC2K</literal>. Next, regardless of whether you are using
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&diskonchip; or ATA compatible compact flash media, you need to add
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an <literal>a:</literal> line at the end of the file. This
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<literal>a:</literal> line should look like:</para>
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<programlisting>a: <replaceable>123456</replaceable> 0 4.2BSD 0 0</programlisting>
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<para>Where <replaceable>123456</replaceable> is a number that is
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exactly the same as the number in the existing <literal>c:</literal>
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entry for size. Basically you are duplicating the existing
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<literal>c:</literal> line as an <literal>a:</literal> line, making
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sure that fstype is <literal>4.2BSD</literal>. Save the file and
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exit.</para>
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<informaltable frame="none" pgwide="1">
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<tgroup cols="2">
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<thead>
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<row>
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<entry align="center">ATA compatible</entry>
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<entry align="center">&diskonchip;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><para><screen>&prompt.root; <userinput>disklabel -B -r /dev/ad0c</userinput>
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&prompt.root; <userinput>newfs /dev/ad0a</userinput></screen></para></entry>
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<entry><para><screen>&prompt.root; <userinput>disklabel -B -r /dev/fla0c</userinput>
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&prompt.root; <userinput>newfs /dev/fla0a</userinput></screen></para></entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
|
|
</step>
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<step>
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<title>Placing your filesystem on the flash media</title>
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|
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<para>Mount the newly prepared flash media:</para>
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|
|
<informaltable frame="none" pgwide="1">
|
|
<tgroup cols="2">
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<thead>
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<row>
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|
<entry align="center">ATA compatible</entry>
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|
|
<entry align="center">&diskonchip;</entry>
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|
</row>
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</thead>
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<tbody>
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|
<row>
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<entry><para><screen>&prompt.root; <userinput>mount /dev/ad0a /flash</userinput></screen></para></entry>
|
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|
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<entry><para><screen>&prompt.root; <userinput>mount /dev/fla0a /flash</userinput></screen></para></entry>
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</row>
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</tbody>
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|
</tgroup>
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|
</informaltable>
|
|
|
|
<para>Bring this machine up on the network so we may transfer our tar
|
|
file and explode it onto our flash media filesystem. One example of
|
|
how to do this is:</para>
|
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|
|
<screen>&prompt.root; <userinput>ifconfig xl0 192.168.0.10 netmask 255.255.255.0</userinput>
|
|
&prompt.root; <userinput>route add default 192.168.0.1</userinput></screen>
|
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|
|
<para>Now that the machine is on the network, transfer your tar file.
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|
You may be faced with a bit of a dilemma at this point - if your
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|
flash memory part is 128 megabytes, for instance, and your tar file
|
|
is larger than 64 megabytes, you cannot have your tar file on the
|
|
flash media at the same time as you explode it - you will run out of
|
|
space. One solution to this problem, if you are using FTP, is to
|
|
untar the file while it is transferred over FTP. If you perform
|
|
your transfer in this manner, you will never have the tar file and
|
|
the tar contents on your disk at the same time:</para>
|
|
|
|
<screen><prompt>ftp></prompt> <userinput>get tarfile.tar "| tar xvf -"</userinput></screen>
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|
|
<para>If your tarfile is gzipped, you can accomplish this as
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|
well:</para>
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|
<screen><prompt>ftp></prompt> <userinput>get tarfile.tar "| zcat | tar xvf -"</userinput></screen>
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|
|
<para>After the contents of your tarred filesystem are on your flash
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|
memory filesystem, you can unmount the flash memory and
|
|
reboot:</para>
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|
|
<screen>&prompt.root; <userinput>cd /</userinput>
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|
&prompt.root; <userinput>umount /flash</userinput>
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|
&prompt.root; <userinput>exit</userinput></screen>
|
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|
|
<para>Assuming that you configured your filesystem correctly when it
|
|
was built on the normal hard disk (with your filesystems mounted
|
|
read-only, and with the necessary options compiled into the kernel)
|
|
you should now be successfully booting your FreeBSD embedded
|
|
system.</para>
|
|
</step>
|
|
</procedure>
|
|
</sect1>
|
|
|
|
<sect1 id="kern.flp">
|
|
<title>Building a <filename>kern.flp</filename> Installation Floppy with
|
|
the fla Driver</title>
|
|
|
|
<note>
|
|
<para>This section of the article is relevant only to those using
|
|
M-Systems &diskonchip; flash media.</para>
|
|
</note>
|
|
|
|
<para>It is possible that your <filename>kern.flp</filename> boot floppy
|
|
does not have a kernel with the <devicename>fla</devicename> driver
|
|
compiled into it necessary for the system to recognize the &diskonchip;.
|
|
If you have booted off of the installation floppies and are told that no
|
|
disks are present, then you are probably lacking the
|
|
<devicename>fla</devicename> driver in your kernel.</para>
|
|
|
|
<para>After you have built a kernel with <devicename>fla</devicename>
|
|
support that is smaller than 1.4 megabytes, you can create a custom
|
|
<filename>kern.flp</filename> floppy image with it by following these
|
|
instructions:</para>
|
|
|
|
<procedure>
|
|
<step>
|
|
<para>Obtain an existing kern.flp image file</para>
|
|
</step>
|
|
|
|
<step>
|
|
<para><screen>&prompt.root; <userinput>vnconfig vn0c kern.flp</userinput></screen></para>
|
|
</step>
|
|
|
|
<step>
|
|
<para><screen>&prompt.root; <userinput>mount /dev/vn0c /mnt</userinput></screen></para>
|
|
</step>
|
|
|
|
<step>
|
|
<para>Place your kernel file into <filename>/mnt</filename>, replacing
|
|
the existing one</para>
|
|
</step>
|
|
|
|
<step>
|
|
<para><screen>&prompt.root; <userinput>vnconfig -d vn0c</userinput></screen></para>
|
|
</step>
|
|
</procedure>
|
|
|
|
<para>Your <filename>kern.flp</filename> file now has your new kernel on it.</para>
|
|
</sect1>
|
|
|
|
<sect1 id="strategies">
|
|
<title>System Strategies for Small and Read Only Environments</title>
|
|
|
|
<para>In <xref linkend="ro-fs">, it was pointed out that the
|
|
<filename>/var</filename> filesystem constructed by
|
|
<filename>/etc/rc.diskless2</filename> and the presence of a read-only
|
|
root filesystem causes problems with many common software packages used
|
|
with FreeBSD. In this article, suggestions for successfully running
|
|
cron, syslog, ports installations, and the Apache web server will be
|
|
provided.</para>
|
|
|
|
<sect2>
|
|
<title>cron</title>
|
|
|
|
<para>In <filename>/etc/rc.diskless2</filename> there is a variable
|
|
named <literal>var_dirs</literal>. This variable consists of a
|
|
space-delimited list of directories that will be created inside of
|
|
<filename>/var</filename> after it is mounted as a memory filesystem.
|
|
<filename>cron</filename> and <filename>cron/tabs</filename> are not
|
|
in that list, and without those directories, cron will complain. By
|
|
inserting <literal>cron</literal>, <literal>cron/tabs</literal>, and
|
|
perhaps even <literal>at</literal>, and <literal>at/jobs</literal> as
|
|
elements of that variable, you will facilitate the running of the
|
|
&man.cron.8; and &man.at.1; daemons.</para>
|
|
|
|
<para>However, this still does not solve the problem of maintaining cron
|
|
tabs across reboots. When the system reboots, the
|
|
<filename>/var</filename> filesystem that is in memory will disappear
|
|
and any cron tabs you may have had in it will also disappear.
|
|
Therefore, one solution would be to create cron tabs for the users
|
|
that need them, mount your <filename>/</filename> filesystem as
|
|
read-write and copy those cron tabs to somewhere safe, like
|
|
<filename>/etc/tabs</filename>, then add a line to the end of
|
|
<filename>/etc/rc.diskless2</filename> that copies those crontabs into
|
|
<filename>/var/cron/tabs</filename> after that directory has been
|
|
created during system initialization. You may also need to add a line
|
|
that changes modes and permissions on the directories you create and
|
|
the files you copy with <filename>/etc/rc.diskless2</filename>.</para>
|
|
</sect2>
|
|
|
|
<sect2>
|
|
<title>syslog</title>
|
|
|
|
<para><filename>syslog.conf</filename> specifies the locations of
|
|
certain log files that exist in <filename>/var/log</filename>. These
|
|
files are not created by <filename>/etc/rc.diskless2</filename> upon
|
|
system initialization. Therefore, somewhere in
|
|
<filename>/etc/rc.diskless2</filename>, after the section that creates
|
|
the directories in <filename>/var</filename>, you will need to add
|
|
something like this:</para>
|
|
|
|
<screen>&prompt.root; <userinput>touch /var/log/security /var/log/maillog /var/log/cron /var/log/messages</userinput>
|
|
&prompt.root; <userinput>chmod 0644 /var/log/*</userinput></screen>
|
|
|
|
<para>You will also need to add the log directory to the list of
|
|
directories that <filename>/etc/rc.diskless2</filename>
|
|
creates.</para>
|
|
</sect2>
|
|
|
|
<sect2>
|
|
<title>ports installation</title>
|
|
|
|
<para>Before discussing the changes necessary to successfully use the
|
|
ports tree, a reminder is necessary regarding the read-only nature of
|
|
your filesystems on the flash media. Since they are read-only, you
|
|
will need to temporarily mount them read-write using the mount syntax
|
|
shown in <xref linkend="ro-fs">. You should always remount those
|
|
filesystems read-only when you are done with any maintenance -
|
|
unnecessary writes to the flash media could considerably shorten its
|
|
lifespan.</para>
|
|
|
|
<para>To make it possible to enter a ports directory and successfully
|
|
run <command>make install</command>, it is necessary for the file
|
|
<filename>/var/db/port.mkversion</filename> to exist, and that it has
|
|
a correct date in it. Further, we must create a packages directory on
|
|
a non-memory filesystem that will keep track of our packages across
|
|
reboots. Because it is necessary to mount your filesystems as
|
|
read-write for the installation of a package anyway, it is sensible to
|
|
assume that an area on the flash media can also be used for package
|
|
information to be written to.</para>
|
|
|
|
<para>First, create a package database directory. This is normally in
|
|
<filename>/var/db/pkg</filename>, but we cannot place it there as it
|
|
will disappear every time the system is booted.</para>
|
|
|
|
<screen>&prompt.root; <userinput>mkdir /etc/pkg</userinput></screen>
|
|
|
|
<para>Now, add a line to <filename>/etc/rc.diskless2</filename> that
|
|
links the <filename>/etc/pkg</filename> directory to
|
|
<filename>/var/db/pkg</filename>. An example:</para>
|
|
|
|
<screen>&prompt.root; <userinput>ln -s /etc/pkg /var/db/pkg</userinput></screen>
|
|
|
|
<para>Add another line in <filename>/etc/rc.diskless2</filename> that
|
|
creates and populates
|
|
<filename>/var/db/port.mkversion</filename></para>
|
|
|
|
<screen>&prompt.root; <userinput>touch /var/db/port.mkversion</userinput>
|
|
&prompt.root; <userinput>chmod 0644 /var/db/port.mkversion</userinput>
|
|
&prompt.root; <userinput>echo <replaceable>20010412</replaceable> >> /var/db/port.mkversion</userinput></screen>
|
|
|
|
<para>where <replaceable>20010412</replaceable> is a date that is
|
|
appropriate for your particular release of FreeBSD</para>
|
|
|
|
<para>Now, any time that you mount your filesystems as read-write and
|
|
install a package, the <command>make install</command> will work
|
|
because it finds a suitable
|
|
<filename>/var/db/port.mkversion</filename>, and package information
|
|
will be written successfully to <filename>/etc/pkg</filename> (because
|
|
the filesystem will, at that time, be mounted read-write) which will
|
|
always be available to the operating system as
|
|
<filename>/var/db/pkg</filename>.</para>
|
|
</sect2>
|
|
|
|
<sect2>
|
|
<title>Apache Web Server</title>
|
|
|
|
<para>Apache keeps pid files and logs in
|
|
<filename><replaceable>apache_install</replaceable>/logs</filename>.
|
|
Since this directory doubtless exists on a read-only filesystem, this
|
|
will not work. It is necessary to add a new directory to the
|
|
<filename>/etc/rc.diskless2</filename> list of directories to create
|
|
in <filename>/var</filename>, to link
|
|
<filename><replaceable>apache_install</replaceable>/logs</filename> to
|
|
<filename>/var/log/apache</filename>. It is also necessary to set
|
|
permissions and ownership on this new directory.</para>
|
|
|
|
<para>First, add the directory <literal>log/apache</literal> to the list
|
|
of directories to be created in
|
|
<filename>/etc/rc.diskless2</filename>.</para>
|
|
|
|
<para>Second, add these commands to
|
|
<filename>/etc/rc.diskless2</filename> after the directory creation
|
|
section:</para>
|
|
|
|
<screen>&prompt.root; <userinput>chmod 0774 /var/log/apache</userinput>
|
|
&prompt.root; <userinput>chown nobody:nobody /var/log/apache</userinput></screen>
|
|
|
|
<para>Finally, remove the existing
|
|
<filename><replaceable>apache_install</replaceable>/logs</filename>
|
|
directory, and replace it with a link:</para>
|
|
|
|
<screen>&prompt.root; <userinput>rm -rf (apache_install)/logs</userinput>
|
|
&prompt.root; <userinput>ln -s /var/log/apache (apache_install)/logs</userinput></screen>
|
|
</sect2>
|
|
</sect1>
|
|
</article>
|
|
|