NAME

sboot − SA110 and SA1100 bootstrap program

SYNOPSIS

From armsd, rdp, or exported styxmon connection: load sboot go

DESCRIPTION

Sboot is a standalone executable for the StrongARM architectures (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 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 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  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 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

If the sboot binary file resides on the host,  it  can  be simply  be  copied  to 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 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. 

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 device can only be used on Demon-based systems, and  will  not work  on  Styxmon-based  systems.   On systems with Styxmon, use the 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 is  the  entire flash, and 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 arguments,  and a short description. 

> [v|d]
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 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 compressed, using gzip format, and  will  be  automatically  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 destination. 

c/usrc dest
Copy  a compressed file from the source to the destination, 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.

e file Examine the specified  file,  using  both  hex  (in 32-bit words) and ascii formats. 

P List  partition  table.  This  shows,  for  each  partition,  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 represents 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 protected.  Sector protection  information  is  not available 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. 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  autoboot 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 autoboot enabled.  In particular, the serial debugger  connection is no longer active. 

EXAMPLES

All these examples are run from the sboot console:

To see the current partition table:

P

Before creating a default partition table,  existing information  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

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

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

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 control-D needs to be typed twice, and when using from DOS/Windows, further followed by a carriage return. 

Change the variable to

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

SEE ALSO

mdb(1), inferno.ini(10.8) styxmon(10.8)

BUGS

It is slightly elaborate for a bootstrap.