OpenBSD FAQ: Installation Guide (original) (raw)

• Overview of the Installation Procedure
• Pre-Installation Checklist
• Downloading OpenBSD
• Creating Install Media
• Performing a Simple Install
• File Sets
• Disk Partitioning
• Bootstrapping Wireless Firmware
• Sending Your dmesg After the Install
• Customizing the Install Process
• Multibooting

Overview of the Installation Procedure

The OpenBSD installer uses a special ramdisk kernel (bsd.rd) that spawns a live environment running entirely in memory. It contains the install script and a small number of utilities needed to perform a complete installation. These utilities can also be useful for disaster recovery.

The ramdisk kernel can be booted from a number of different sources:

• CD/DVD
• USB drive
• An existing partition
• Over the network (PXE or othernetwork boot options)
• Floppy disk Not every platform supports all of these options.

If you have a running OpenBSD system, bsd.rd is all you need to reinstall or upgrade to a newer version. To do so,download and verify the new bsd.rd, place it on an existing filesystem, and boot from it. The general method of booting bsd.rd is to change your boot kernel from /bsd to /bsd.rd through whatever means used on your platform.

Booting from bsd.rd on an amd64 system can be done like so:

Using drive 0, partition 3. Loading...... probing: pc0 com0 com1 mem[638K 1918M a20=on] disk: hd0+ hd1+

OpenBSD/amd64 BOOT 3.33 boot> bsd.rd

This will boot the kernel named bsd.rd from the first partition of the first recognized hard disk.

If you need to specify a different drive or partition, just prefix the kernel name with its location. The following example would boot from the fourth partition of the second hard drive:

Using drive 0, partition 3. Loading...... probing: pc0 com0 com1 mem[638K 1918M a20=on] disk: hd0+ hd1+

OpenBSD/amd64 BOOT 3.33 boot> boot hd1d:/bsd.rd

OpenBSD boot loaders are documented in the architecture-specificboot(8) man pages.

Pre-Installation Checklist

Before you start, you should have some idea what you want to end up with. A few things worth considering beforehand:

• Machine name
• Hardware installed and available:
  • Verify compatibility with your hardware. You may want to consult the platform-specific installation notes, especially if you're using one of the non-x86 CPU architectures. They contain detailed instructions and any possible caveats:
    [alpha] [amd64] [arm64] [armv7] [hppa] [i386] [landisk] [loongson] [luna88k] [macppc] [octeon] [powerpc64] [riscv64] [sparc64]
  • If wireless internet is your only networking option, does the card require additional firmware? If so, read the section onbootstrapping wireless firmware.
• Install method to be used
• Desired disk layout:
  • Does existing data need to be saved elsewhere?
  • Will OpenBSD coexist on this system with another OS? If so, how will each system be booted? Will you need to install a boot manager?
  • Will the entire disk be used for OpenBSD, or do you want to keep an existing partition/OS? (or space for a future one)
  • How do you wish to sub-partition the OpenBSD part of your disk?
  • Do you want disk encryption?
• Network settings, if not using DHCP:
  • Domain name and DNS address
  • IP address and subnet masks for each NIC
  • Gateway address

Downloading OpenBSD

The following installation images are available:

Images can also be downloaded from a number of alternatemirror sites.

An SHA256 file containing checksums can be found in the same directory as the installation files. You can confirm that none of the downloaded files were mangled in transit using the sha256(1) command.

$ sha256 -C SHA256 miniroot.img* (SHA256) miniroot76.img: OK

Or, if you're using the GNU coreutils:

$ sha256sum -c --ignore-missing SHA256 miniroot76.img: OK

However, this only checks for accidental corruption. You can use signify(1) and theSHA256.sig file to cryptographically verify the downloaded image.

$ signify -Cp /etc/signify/openbsd-76-base.pub -x SHA256.sig miniroot.img* Signature Verified miniroot76.img: OK

Note that the signify package on other operating systems may not include the required public key, or it may be installed in another location.

The install76.iso and install76.img images do not contain an SHA256.sig file, so the installer will complain that it can't check the signature of the included sets:

Directory does not contain SHA256.sig. Continue without verification? [no]

This is because it would make no sense for the installer to verify them. If someone were to make a rogue installation image, they could certainly change the installer to say the files were legitimate. If the image's signature has been verified beforehand, it is safe to answer "yes" at that prompt.

Flash Drives

A bootable USB flash drive can be created by attaching the target device and copying over the image with dd(1).

Using OpenBSD, assuming the device was recognized as sd6:

dd if=install.img of=/dev/rsd6c bs=1M*

Note that the raw I/O device is used: rsd6c rather thansd6c.

Details of this will vary on other platforms. If you're using a different OS, be sure to select the appropriate device name: /dev/sdX on Linux or /dev/rdiskX on macOS for example.

CD-ROMs

You can create a bootable CD-ROM on OpenBSD by usingcdio(1).

cdio tao cd.iso*

Performing a Simple Install

If you need instructions on booting from your preferred media, check the relevant platform page of your machine.

The installer is designed to install OpenBSD in a very usable default configuration with a minimum of user intervention. In fact, you can often just hit <Enter> to get a good OpenBSD install, moving your hands to the rest of the keyboard only to enter the root password.

After the dmesg(8) is shown, you will see the first installer question:

... root on rd0a swap on rd0b dump on rd0b erase ^?, werase ^W, kill ^U, intr ^C, status ^T

Welcome to the OpenBSD/amd64 7.6 installation program. (I)nstall, (U)pgrade, (A)utoinstall or (S)hell?

Choose (I)nstall and follow the instructions.

File Sets

The complete OpenBSD installation is broken up into a number of file sets:

New users are recommended to install all of them.

Some libraries from xbase76.tgz, like freetype or fontconfig, can be used outside of X by programs that manipulate text or graphics. Such programs will usually need fonts, either from xfont76.tgz or font packages. For the sake of simplicity, the developers decided against maintaining a minimalxbase76.tgz set that would allow most non-X ports to run.

Adding a File Set After Install

If you chose to skip some file sets at install time, you might realize later that you really do need them after all. Simply boot bsd.rd from your root file system and choose(U)pgrade. When you get to the list of file sets, select the ones you need.

Disk Partitioning

OpenBSD can be installed in as little as 512MB, but using a device that small is something for advanced users. Until you have some experience, 8GB or more disk space is recommended.

Unlike some other operating systems, OpenBSD encourages users to split their disk into a number of partitions, rather than just one or two large ones. Some of the reasons for doing so are:

• Security: Some of OpenBSD's default security features rely on filesystemmount options such asnosuid, nodev, noexec orwxallowed.
• Stability: A user or a misbehaved program can fill a filesystem with garbage if they have write permissions for it. Your critical programs, which hopefully run on a different filesystem, do not get interrupted.
• fsck(8): You can mount partitions that you never or rarely need to write to asreadonly most of the time, which will eliminate the need for a filesystem check after a crash or power interruption. The installer will create a partitioning plan based on the size of your hard disk. While this will not be a perfect layout for all people, it provides a good starting point for figuring out what you need. Read about disklabel's defaults forautomatic disk allocation and thehier(7) man page before making decisions about custom partitioning schemes.
• Since some packages need to be started from awxallowed filesystem, it is recommended to have a separate/usr/local partition.
• Very small partitions can become troublesome when you need to upgrade.
• A /home partition can be nice. New version of the OS? Leave your /home partition untouched, wipe and reload everything else.
• You may also want to create analtroot partition for backing up your root filesystem.
• A system exposed to the internet should have a separate /var and maybe even a separate /var/log.
• Compiling some ports from source can take huge amounts of space on your /usr and /tmp partitions.

Bootstrapping Wireless Firmware

For licensing reasons, some firmware cannot be directly distributed with OpenBSD. The fw_update(8) tool will automatically download and install any missing firmware, but this requires a working internet connection.

In the case of certain hardware configurations, such as a laptop with no ethernet port, the user will have to manually download and install the firmware in order to get online for the first time. This can be done pre-installation, by adding the firmware files to the install media, or after the OS has been installed from a CD or disk.

Adding firmware files to the install media will not enable the hardware during the installation process. They will be added to the target disk, so the hardware can be used after the first boot into the installed system.

Start by finding the wireless adapter'sinterface namewith dmesg(8).

From an existing OpenBSD installation, mount the install image as a vnode disk with vnconfig(8) and use fw_update(8) to download the required files to it. This example uses firmware for aniwm(4) card:

vnconfig install76.img

vnd0

mount /dev/vnd0a /mnt

fw_update -Fv -p /mnt iwm

umount /mnt

vnconfig -u vnd0

The resulting file can then be used to createa bootable install image with the necessary firmware.

If you don't have an existing OpenBSD system with internet access, use another computer to download the appropriate file from http://firmware.openbsd.org/firmware/ and put it on a USB drive that's readable by OpenBSD. Then, on the OpenBSD machine,mount(8) the drive and usefw_update(8) to install it from there.

Sending Your dmesg After the Install

After a successful install, look at the output of thedmesg(8) command and see if anything stands out. If a device shows up as not configured, this means that it is not currently supported by the kernel. This may be improved in the future by sending the dmesg. A quote from /usr/src/etc/root/root.mail:

If you wish to ensure that OpenBSD runs better on your machines, please do us a favor (after you have your mail system configured!) and type something like:

**(dmesg; sysctl hw.sensors) | **

mail -s "Sony VAIO 505R laptop, apm works OK" dmesg@openbsd.org

so that we can see what kinds of configurations people are running. As shown, including a bit of information about your machine in the subject or the body can help us even further. We will use this information to improve device driver support in future releases. (Please do this using the supplied GENERIC kernel, not for a custom compiled kernel, unless you're unable to boot the GENERIC kernel. If you have a multi-processor machine, dmesg results of both GENERIC.MP and GENERIC kernels are appreciated.) The device driver information we get from this helps us fix existing drivers. Thank you!

Alternatively, save your dmesg output to a text file and send us its contents:

$ (dmesg; sysctl hw.sensors) > ~/dmesg.txt

Please configure your email client to use plain text. In particular, do not use HTML formatting or forced line breaks. Put the dmesg into the body of the mail, not as an attachment.

Customizing the Install Process

The site76.tgz File Set

The OpenBSD install and upgrade scripts allow the selection of a user-created set called site76.tgz. Like the official file sets, this is atar(1) archive rooted in/ and untarred with the -xzphf options. It is installed last, so it can be used to complement and modify the files from a default install. Furthermore, it is possible to use hostname-dependent sets namedsite76-$(hostname -s).tgz.**Note:**If you intend to provide the sets over HTTP(s), place site76.tgzin your source directory and include it in your index.txt. It will then be an option at install time.

The install.site and upgrade.site Scripts

If the site76.tgz file set contains an executable file/install.site, the installer runs it withchroot(8)based at the freshly installed system's root. Similarly, the upgrade script runs /upgrade.site. The latter can be placed in the system's root directory before rebooting for the upgrade.

Example usage:

• Set the system time.
• Do an immediate backup/archive of the new system before you expose it to the rest of the world.
• Have a set of arbitrary commands be run after the first boot. This will happen if install.site is used to append any such commands to anrc.firsttime(8) file (appending to this file is necessary since the installer itself may write to this file). At boot time, rc.firsttime is executed once then deleted.

Multibooting

Multibooting is having several operating systems on one computer, with some means of selecting which OS is to boot. You may want to familiarize yourself with theOpenBSD boot process before you start. A brief introduction to fdisk(8)is in the section on using OpenBSD's fdisk.

If you are adding OpenBSD to an existing system, you will probably need to create some free space before installing OpenBSD. In addition to your existing system's native tools,gpartedmay be useful for deleting or resizing existing partitions. Preferably use one of the four primary MBR partitions for booting OpenBSD. Extended partitions may not work.

rEFInd is reported to usually work.GRUB is reported to usually fail. In either case, you are completely on your own.

Windows

The Boot Configuration Data (BCD) store allows multiple versions of Windows to be booted through bcdedit. A good introduction can be found inthis article. If you want a GUI alternative, you may want to tryEasyBCD.

You will need a copy of your OpenBSD install'sPartition Boot Record (PBR). You can copy it to a file using a process similar to:

dd if=/dev/rsd0a of=openbsd.pbr bs=512 count=1

where sd0a is your boot device, and you will need to get the file openbsd.pbr to your Windows system partition.

Once OpenBSD's PBR is copied to the Windows system partition, you need a shell with administrative privileges to run the following commands:

C:\Windows\system32> bcdedit /create /d "OpenBSD/i386" /application bootsector The entry {0154a872-3d41-11de-bd67-a7060316bbb1} was successfully created. C:\Windows\system32> bcdedit /set {0154a872-3d41-11de-bd67-a7060316bbb1} device boot The operation completed successfully. C:\Windows\system32> bcdedit /set {0154a872-3d41-11de-bd67-a7060316bbb1} path \openbsd.pbr The operation completed successfully. C:\Windows\system32> bcdedit /set {0154a872-3d41-11de-bd67-a7060316bbb1} device partition=c: The operation completed successfully. C:\Windows\system32> bcdedit /displayorder {0154a872-3d41-11de-bd67-7060316bbb1} /addlast The operation completed successfully.

Note that OpenBSD expects the computer's real-time clock to be set to Coordinated Universal Time (UTC). See this section for more info.