---
name: "boot_sparc64"
section: "8"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/boot_sparc64"
---

# boot\_sparc64(8)

sparc64 system bootstrapping procedures

## NAME

**boot\_sparc64** – sparc64 system bootstrapping procedures

## DESCRIPTION

### System starts

When powered on, after a panic, or if the system is rebooted via [reboot(8)](/reboot/8.md) or [shutdown(8)](/shutdown/8.md), the PROM will proceed to its initialization, and will boot an operating system if autoboot is enabled.

### Boot process description

The sparc64 boot process is split into two parts: a small first-stage bootblock that is written into the superblock area of a partition( and hence is limited in size to SBSIZE - DEV\_BSIZE bytes), and a second-stage boot program that resides in the filesystem proper. The first-stage bootblock is loaded into memory by the PROM. After it receives control, it loads the second-stage boot program **ofwboot** from the filesystem. The second-stage boot program uses the device driver interface to the PROM and the stand-alone filesystem code in *libsa.a* to locate and load the kernel. The first-stage bootblock and second-stage boot program can be found in */usr/mdec/bootblk* and */usr/mdec/ofwboot* respectively. The second-stage boot program commonly resides in the root directory as */ofwboot*.

The boot program attempts to load the kernel from the selected boot device, which must currently be an SCSI (*sd*) or IDE (*wd*) disk drive, or a CD-ROM (*cd*), or an SCSI tape drive (*st*).

The UltraSPARC Open Firmware will normally look for a bootloader on the device specified by the *boot-device* variable. The OpenBSD bootloader will then look for a kernel named *bsd* by default, unless the *boot-file* variable contains a filename, or a different filename has been specified in the boot command. To reset this variable to its default, empty, value, type the following:

**ok** set-default boot-file

Autoboot is enabled by setting the *auto-boot?* variable to “true”, and is the factory default.

### Boot process options

The following options are recognized:

- **-a**

  Prompt for the root filesystem and swap devices after the devices have been configured.

- **-c**

  Enter the “User Kernel Configuration” mode upon startup (see [boot\_config(8)](/boot_config/8.md)).

- **-d**

  Enter the debugger, [ddb(4)](/ddb/4.md), as soon as the kernel console has been initialized.

- **-s**

  Boot the system single-user. The system will be booted multi-user unless this option is specified.

### Accessing the PROM during runtime

If the [sysctl(8)](/sysctl/8.md) variable *ddb.console* is enabled, at any time you can break back to the ROM by pressing the ‘L1’ (also known as the “stop key”) and ‘a’ keys at the same time (if the console is a serial port the same is achieved by sending a “break”), and entering **machine** **prom** at the prompt. If you do this accidentally you can continue whatever was in progress by typing **go** at the PROM prompt, and then **cont** to return to the system.

## FILES

- */bsd*

  default system kernel

- */bsd.rd*

  standalone installation kernel, suitable for disaster recovery

- */usr/mdec/bootblk*

  primary bootstrap for “ffs” file system

- */usr/mdec/ofwboot*

  secondary bootstrap (usually also installed as */ofwboot*)

- */usr/mdec/ofwboot.net*

  network bootstrap

- */usr/mdec/ofwbootfd*

  floppy disk bootstrap

## SEE ALSO

[ddb(4)](/ddb/4.md), [softraid(4)](/softraid/4.md), [boot\_config(8)](/boot_config/8.md), [halt(8)](/halt/8.md), [init(8)](/init/8.md), [installboot(8)](/installboot/8.md), [reboot(8)](/reboot/8.md), [savecore(8)](/savecore/8.md), [shutdown(8)](/shutdown/8.md)