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.Dd October 7, 2013
.Dt ALTBOOT 8 sandpoint
.Os
.Sh NAME
.Nm altboot
.Nd program to boot
.Nx
kernel from disk or network
.Sh DESCRIPTION
.Nm
is a standalone program which works on top of a
.Tn NAS
product's bootloader.
It is capable of loading a
.Nx
kernel from an
.Tn IDE
or
.Tn SATA
disk drive, or via network with
.Tn NFS
or
.Tn TFTP
protocol.
.Nm
can be stored in flash ROM.
Typically you will first copy it from flash into RAM and then invoke
it there to boot the
.Nx
kernel.
.Pp
.Nm
runs in conjunction with popular
.Tn U-Boot/PPCBoot
bootloaders used by
.Tn NAS
products.
With an appropriate boot command line, saved in the environment,
.Nm
can load and start a
.Nx
kernel without manual intervention.
The original
.Tn U-Boot/PPCBoot
bootloaders remain useful and altboot works as a functional extension
of them.
.Sh EXAMPLES
.Nm
occupies less than 128KB in volume and can be stored to any vacant
space of the system's flash.
It is made to run at RAM address offset 0x0100'0000.
.Tn U-Boot/PPCboot
is instructed to copy the program to RAM in this way:
.Pp
.Dl => cp.b fffe0000 1000000 20000
.Pp
Here 0xfffe'0000 is the flash address where
.Nm
is stored while 0x0100'0000 is the RAM address to copy to.
.Pp
The invocation syntax is:
.Pp
.Dl => go 1000000 Ar ide:N Ar opt1 Ar opt2 ... Ar bootname
.Bl -tag -width xx
.It Va ide:N
where
.Ar N
is a string of digits, which defines the number of connected drives on each
PATA channel.
This option is useful to avoid the delays, when
.Nm
is trying to detect a non-existing drive.
Examples:
.Bl -tag -width xx
.It ide: Ns Ar 10
A single master drive on the first channel.
Nothing on the second channel.
.It ide: Ns Ar 22
A master and slave drive on both channels of the first controller.
.It ide: Ns Ar 1111
A master drive on each channel.
The first two digits belong to the first
controller, the last two to the second controller.
.El
.Pp
Unspecified digits will be read as
.Ar 0 .
The
.Ar ide
option has only a meaning for PATA disks.
Omitting it makes it default to
.Ar ide:10 .
.Pp
.It Va optN
multi, auto, ask, single, ddb, userconf, norm, quiet, verb,
silent, debug
.Pp
Omitting optN makes
.Nm
default to multi-user mode boot.
.Pp
N.B., the maximum number of allowed go command arguments varies
and depends on the
.Tn U-Boot/PPCBoot
buildtime configuration.
.It Va bootname
One of the following:
.Pp
.Dl nfs: Ns Ar filename
.Dl nfs:
.Dl tftp: Ns Ar filename
.Dl tftp:
.Dl wd Ns Ar Np : Ns Ar filename
.Dl wd Ns Ar Np :
.Dl mem: Ns Ar address
.Dl net:
.Pp
The last one is a synonym for
.Dq nfs .
.It nfs: Ns Va filename
issue a
.Tn DHCP
request to determine the
.Tn IP
address and download
.Ar filename
from the
.Tn NFS
server.
.It nfs:
target file is determined by
.Sy filename
field of
.Pa /etc/dhcpd.conf
.It tftp: Ns Va filename
issue a
.Tn DHCP
request to determine
.Tn IP
address and download
.Ar filename
from the
.Tn TFTP
server.
.It tftp:
target file is determined by
.Sy filename
field of
.Pa /etc/dhcpd.conf
.It wd Ns Va Np : Ns Va filename
load the
.Tn ELF
.Nx
kernel
.Ar filename
from an
.Tn FFSv2
or
.Tn FFSv1
filesystem.
.Ar N
is a number to distinguish the target drive.
.Ar p
is a partition specifier.
When omitted, partition
.Sq a
is assumed.
.Dq wd0a
means partition
.Sq a
of the first disk drive.
.It wd Ns Va Np :
use filename
.Dq netbsd
for booting the
.Tn ELF
.Nx
kernel.
.It mem: Ns Va address
boots the
.Tn ELF
.Nx
kernel from any address in memory.
The
.Ar address
argument has to be specified as a hexadecimal number and denotes the
start address of the
.Tn ELF
image in memory.
.El
.Pp
.Nm
can boot from RAID 1 partitions, but only if the RAID partition is the
first partition on the disk.
.Pp
.Tn U-Boot/PPCBoot
provides a way to run a short list of commands right after power-on.
The following is a procedure to setup the system for starting
.Nx
after a 5 second delay, allowing the user to break into interactive
mode.
Note that a backslashed
.Sq \&;
is necessary to enter the script correctly.
.Bd -literal -offset indent
=> setenv bootcmd cp.b fffe0000 1000000 20000\e; go 1000000 wd0:
=> setenv bootdelay 5
=> saveenv
.Ed
.Pp
When
.Tn U-Boot/PPCBoot
is lacking important commands like
.Tn cp
or
.Tn go ,
or is unable to save the environment, then there is still the option to
replace the
.Tn Linux
kernel module by
.Pa altboot.img
and save it to the same address in flash ROM.
In this case you have only two options left to pass arguments:
.Pp
.Bl -bullet -compact
.It
Enter the interactive command line mode, after
.Nm
has started.
This requires a serial console.
.It
Write a fixed command line into flash, replacing the
.Tn Linux
initrd image.
The command line is a normal
.Tn ASCII
file, started by the identifier
.Em altboot:
and terminated by any control character between 0 and 31.
Example:
.Dl altboot:silent ide:1111 wd0:netbsd
.El
.Sh SEE ALSO
.Xr dhcpd 8 ,
.Xr diskless 8 ,
.Xr nfsd 8 ,
.Xr raidctl 8 ,
.Xr tftpd 8
.Sh HISTORY
The
.Nx Ns Tn /sandpoint
.Nm
first appeared in
.Nx 6.0 .
.Sh BUGS
The Realtek Gigabit Ethernet driver does not work correctly at 1000 Mbps.
Another known problem of this driver is that it runs into a timeout after
a coldstart.
The system has to be rebooted at least once to make it work.