SBOOT(10.8) (Strongarm) SBOOT(10.8)
NAME
sboot - SA110 and SA1100 bootstrap program
SYNOPSIS
From armsd, rdp, or exported styxmon connection:
.}f
load sboot
go
DESCRIPTION
Sboot is a standalone executable for the StrongARM architec-
tures (SA110 and SA1100) that loads and starts a program in
Inferno boot format (for the ARM, this is either an AIF or
Plan9-style executable). Sboot loads the program at the
entry address specified by the header, usually `0x8000' on
the SA1100. After loading, control is passed to the entry
location specified in the executable's header.
Loading sboot from armsd
If a board with the old Demon-based monitor is being used,
there are at least four ways that sboot can be loaded from
the ARM debugger armsd. If the sboot binary file resides
on the host in the current directory, it can be loaded
with:
load sboot
go
If sboot has already been loaded into the flash memory or
ROM at its default offset (`0x8000' on the SWoRD board),
then this shortcut can be used:
pc=0x40
go
If sboot has been loaded into the flash memory or ROM at a
different address, then the following sequence can be
used:
r0=<offset of sboot>
pc=0x48
go
Finally, if the system has been set up to autoboot, by
setting the autoboot vector (described with the P command,
below), then sboot will be run automatically upon booting
and will attempt to load the kernel automatically.
After sboot is started, unless it is in autoboot mode, a
command prompt (`>>>') will appear on the debugger
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console.
Loading sboot from rdp
With rdp, a small armsd replacement that runs under Inferno,
sboot will automatically start unless the -c option is given
to rdp. If the -c option is used (`enter command mode'), the
`sb' mash(1) command provided in /usr/ddk/lib/mashinit can
be used to start sboot. Alternatively, use the same commands
as with armsd.
Loading sboot from Styxmon
From styxmon(10.8), there are several ways to load sboot.
All of the following examples assume that styxmon has been
mounted on `/n/rdbg'.
If the sboot binary file resides on the host, it can be
simply be copied to `/n/rdbg/boot' to have it copied onto
the board and started.
If sboot has already been loaded into the flash memory or
ROM at its default offset (0x8000 on the SWoRD board),
then it can be executed with:
echo E > /n/rdbg/ctl
If sboot has been loaded into the flash memory or ROM at a
different address, then the following sequence can be
used:
echo E0xoffset >/n/rdbg/ctl
Finally, if the system has been set up to autoboot, by
setting the autoboot vector (described in the P command,
below), then sboot will be run automatically upon booting
and will attempt to load the kernel automatically.
After loading sboot via styxmon(10.8), it will export the
flash partitions into the namespace, with names such
as /n/rdbg/flash0sboot. These files can be copied to and
from like ordinary files. It will also export a temporary
device, called `/n/rdbg/tmp' which is mirrored by the T!
device discussed below.
File and Device Names
From the sboot shell prompt, most commands will take file-
names as arguments. Filenames can represent devices, or
files in the more traditional sense, but in either case a
device is always specified. Most filenames are in the
form device!unit!file. Some devices have the simpler form
device!file, or device!argument. This format is used to be
consistent with the Inferno boot loaders on other platforms.
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Supported devices are:
m!address
Memory. The single argument tells the base address to
start at, and defaults to 0 if omitted.
Z[!number]
Zero device. The single optional argument tells the
number of zeros to supply, otherwise an infinite
source is available. This is useful for clearing
areas of memory, disk blocks, partition tables, etc.
D!debug_file
The host debugger file system. The unit is omitted,
and the file represents a file on the host machine.
These host files are accessed internally via the
bootparam interface (see /os/sa1100/bootparam.h). The
`D!' device can only be used on Demon-based systems,
and will not work on Styxmon-based systems. On
systems with Styxmon, use the `T!' device instead,
or directly access the exported flash partitions.
F!partition_name
Flash memory. The unit can be either the number or
name of a partition, where `all' is the entire
flash, and `partition' is the partition table.
T! Temporary file. This exists only for styxmon-based
boards. It will grow as needed, and can be referred
to as T! (from sboot commands), or when mounted as
/n/rdbg/tmp.
When accessed from sboot, shell commands, filenames may
optionally be followed by an offset and/or a length, in
the following format:
filename@offset [,length]
The length is relative to the starting offset. If an offset
and/or length is given and no device/filename is specified,
then the m memory device is used by default. Examples
can be found at the end of this document.
Commands
The following commands are available (listed in alphabetical
order):
? List commands, showing for each command: the command
character, the minimum and maximum number of argu-
ments, and a short description.
> [v|d]
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Redirect output to video (v), or debugger (d).
< [k|d]
Redirect input from keyboard (k), or debugger (d).
= List all environment variables. Those with asterisks
to the left of them are pseudo-variables that have
special meaning, and aren't passed on to programs as
part of the environment.
variable=value
Set a variable to the specified value, which can be
either a string or number depending upon the meaning
of the variable. Variables can be substituted into
the command line using `$variable', similar to many
shell programs.
B Show BootParam information.
b[ file ][ args ] ...
Boot from the specified file/device. Boot arguments
are optional. The file to boot from is optional,
and if it is not specified, the command b $bootfile
$bootargs will be substituted, using the bootfile and
bootargs environment variables. If the boot file is
not specified, and the variable bootfile is not set,
an error will be reported. The boot file can be com-
pressed, using gzip format, and will be automati-
cally uncompressed prior to execution.
csrc dest
Copy a file from the source to the destination. A
dash (-) can be specified to mean either standard input
for the source, or standard output for the destina-
tion.
c/usrc dest
Copy a compressed file from the source to the destina-
tion, uncompressing it before writing it. This takes
a file that was compressed using the gzip format.
D addr value
Deposit the given 32-bit value at the specified
address.
d file val ...
Deposit one or more values into the given file or
device, using 32-bit words.
E addr
Examine the 32-bit word at the specified address.
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e file
Examine the specified file, using both hex (in
32-bit words) and ascii formats.
P List partition table. This shows, for each par-
tition, the partition device number, the starting
offset, the total size, permissions, flags, and
name. It also shows the autoboot offset. Note that if
flash memory exists, F!all exists, and represents the
entire flash memory. Also, if an area has been set
aside for a partition table, then F!partition rep-
resents that area. All other partitions are
reconfigurable.
P/a number
Enable/disable autoboot. Given a partition device
number, this will set autoboot to occur from the
specified partition. This will also set the internal
vector used for finding sboot in debug mode. Setting
this to 0 will disable autoboot, but will not change
the internal sboot vector. Generally, the partition
holding sboot should be used for autobooting.
WARNING: setting this to anything other than 0
or the sboot partition may make the flash unusable, and
might require using an EEPROM burner to reprogram
the flash. Even setting the autoboot to load sboot
could be dangerous. The autoboot sequence should
first be tested with the A command to make sure it
behaves as expected, and also to make sure that some
means of disabling it is accessible.
P/d number
Delete the specified partition.
P number start size perm flags name
Create a partition. The permissions are specified in
octal as standard Inferno-style permissions (see sys-
stat(2)). Generally, the flags should be set to 0.
P/m Show a map of the entire flash, with sectors, offsets,
and sizes, and whether or not the sector is pro-
tected. Sector protection information is not avail-
able on all flash devices.
P/u number
Unprotect the sectors for the specified partition.
Changing sector protection is not available on all
flash devices.
P/p number
Protect the sectors for the specified partition.
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Changing sector protection is not available on all
flash devices.
S file
Stat a file. Get information about the requested
file or device.
T[repeat]
Show title. This will cycle through the standard
title startup sequence. Given a non-zero parameter,
it will cycle indefinitely.
Autoboot
When the autoboot vector is set in the flash to run sboot
automatically (using the P command), sboot will first cycle
through the title sequence, and then try to boot from the
file specified by the bootfile environment variable, as if
the following commands had been typed:
T 0
b $bootfile $bootargs
The sequence to disable autoboot varies, depending upon
the customized autoboot code, but with the standard auto-
boot sequence it is as follows:
When the title screen starts to fade in, press and hold
the Esc (escape) key. Properly timed, this stops the
standard kernel boot, and the system instead displays a
screen asking whether to go into maintenance mode. From
this screen, press control-D to disable autoboot. Control-E
may be pressed to re-enable autoboot. In this manner, it
is possible to test autoboot first with the A command, then
press Esc and control-E to enable autoboot, ensuring that
it will be possible to reach the screen to turn it off
again later.
Autoboot can also be cleared by using an EEPROM programmer
to rewrite the boot monitor to the flash.
From the sboot prompt, autoboot can be turned off with the
command:
P 0
It should be noted, however, that the sboot prompt cannot
be easily reached once the machine is restarted with auto-
boot enabled. In particular, the serial debugger connec-
tion is no longer active.
EXAMPLES
All these examples are run from the sboot console:
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To see the current partition table:
P
Before creating a default partition table, existing infor-
mation first must be cleared. This can be done by copying
from the zero device to the partition table:
c Z!200 F!partition
Create a new partition table with some sample partitions
(assuming a 4MB flash):
P 0 0 8000 644 0 demon
P 1 8000 18000 644 0 sboot
P 2 20000 80000 666 0 kern
P 3 a0000 80000 666 0 kern2
P 4 120000 280000 666 0 fs
Boot a kernel that resides in the host filesystem
(where armsd is running):
b D!infernosword
Boot a compressed kernel:
b D!infernosword.gz
Download a new kernel into flash, after first compressing
the kernel with gzip:
c D!infernosword.gz F!kern
Download a compressed file system to the board, uncompress
it, and save it to a flash partition called `fs':
c/u D!swordfs.gz F!fs
Boot the kernel from flash:
b F!kern
To boot a kernel that needs to use the serial line for
some other purpose (such as a PPP link), and to be able
to switch the line while the kernel is uncompressing, it
is necessary to redirect the output to the screen
first, instead of the default debugger console. This
can be accomplished with:
> v
b F!kern
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Examine memory, for instance 200 bytes at offset 4000:
e @4000,200
Alternatively, this format could be used to quickly examine
a single 32-bit word:
E 4000
Deposit three values in memory, for instance the values 1,
2, and 3 at offset 0xa94 (in 32-bit words):
d @a94 1 2 3
Alternatively, to change a single value, this format could
be used:
D a94 1
Enter new lines directly into the plan9.ini partition, first
zero it out to be safe:
c Z!1000 F!plan9.ini
Copy from standard input to the partition `plan9.ini':
c - F!plan9.ini
After entering the new lines, end the input with
control-D. When typing directly on the device, this only
has to be typed once. From `armsd', control-D needs to
be typed twice, and when using `armsd' from DOS/Windows,
further followed by a carriage return.
Change the `bootfile' variable to `F!kern2':
bootfile=F!kern2
Change the default radix to 10 (it defaults to 16):
r=10
SOURCE
/os/boot/net
/os/boot/port
/os/boot/styxmon
/os/boot/sa1100
FILES
swordmon
sboot
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SEE ALSO
mdb(1), inferno.ini(10.8) styxmon(10.8)
BUGS
It is slightly elaborate for a bootstrap.
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