BOOT(8) | System Manager's Manual (emips) | BOOT(8)

# NAME

`boot` —
system bootstrapping procedures

# DESCRIPTION

The NetBSD kernel is started by placing it near the beginning of physical memory and transferring to the entry point. Since the system is not reenterable, it is necessary to read it in from disk or the network each time it is to be bootstrapped.

## Power fail and crash recovery

FPGA devices lose their content upon loss of power and must be re-programmed. This is usually accomplished via a JTAG cable programmer, or using a FLASH device. Once the eMIPS processor has been programmed into the FPGA, the system will normally boot itself. An automatic consistency check of the file systems will be performed, and unless this fails, the system will resume multi-user operations.

# Xilinx XUP, ML401 and ML402

On these systems the kernel is normally read in from disk. The path used for automatic booting is `/netbsd`, but it can be overridden in the optional file `/boot.config` stored in the root of the disk filesystem. The user can also type a different filename and a combination of boot options.

# BeSquare BEE3

On this system there is no local disk and booting over the network is the only option. Network boot can also be explicitly selected by hitting `f` at the boot loader prompt.

# KERNEL ARGUMENTS

At the boot loader prompt, the user may boot NetBSD with a number of options that are passed to the kernel unmodified. Parsing of these options is defined in the file `/sys/boot_flag.h` Some additional flags are as follows.

`e`
  Empty -- this argument requests NetBSD to ignore all symbolic information and empty its initial symbol table.
`n`
  Name -- Prompt for the root file system device, the system crash dump device, and the path to init(8).
`N`
  NoName -- Do not prompt for the root file system device, the system crash dump device, and the path to init(8). If the configured-in devices are present, use them.
`s`
  Single -- Boot only to single-user mode.

# SEE ALSO

ddb(4), halt(8), init(8), installboot(8), rc(8), reboot(8), savecore(8), shutdown(8)

# HISTORY

The `boot` command is currently under development.

October 5, 2013 | NetBSD 9.5