boot —
system bootstrapping procedures
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.
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.
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.
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.
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.
 
The boot command is currently under development.