STYXMON(10.8) (Strongarm) STYXMON(10.8)
NAME
styxmon - first stage bootstrap for SA110 and SA1100
SYNOPSIS
echo b9600 >/dev/eia0ctl
mount -A /dev/eia0 /n/rdbg
DESCRIPTION
Styxmon is the first stage bootstrap program for Inferno on
various Strongarm platforms. It also acts as a Styx server,
responding to T messages on the serial port, allowing a
debugging host to do an unauthenticated mount (see bind(1))
of the device to access it.
Styxmon is burned in the non-volatile (flash) RAM at an
address such that processor reset executes it. Styxmon is
responsible for basic machine initialization, loading and
executing the secondary bootloader (or any other standalone
program). It provides a specialised interface to the stan-
dalone program, used only by sboot(10.8); see the source
code.
Initially, styxmon exports four files into the namespace.
Programs that are run from Styxmon, such as sboot, can add
additional files to the namespace that is exported.
/n/rdbg/boot
/n/rdbg/cons
/n/rdbg/ctl
/n/rdbg/mem
These files are described below.
boot Any file copied here will be executed, if it has a
standard Plan 9 or AIF (ARM) header. For example, to
boot `sbsword.aif' (the AIF executable for sboot), do
the following:
cp sbsword.aif /n/rdbg/boot
This is equivalent to finding a region of memory that
is known to be unused, and doing the following set of
commands (assuming that such a region exists at
`0x10000'):
dd -if sbsword.aif -of /n/rdbg/mem -bs 1024 -oseek 64
echo e0x10000 > /n/rdbg/ctl
cons The console file, which can be read to get console
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STYXMON(10.8) (Strongarm) STYXMON(10.8)
output; when written to, the data is sent as console
input to any program currently running on the device.
For instance, to keep an ongoing log of console out-
put:
cat /n/rbdg/cons&
If sboot is running, a `P' command can be typed to it
with:
echo P > /n/rdbg/cons
For an interactive console:
cat /n/rbdg/cons&
cat >/n/rbdg/cons
ctl The control file, to which commands can be written,
described below.
mem A seekable file that represents all of the device's
memory. It should be used with utilities that selec-
tively seek and read or write parts of it, such as
dd(1) and mdb(1).
The control file ctl accepts the following commands:
Eoffset
Execute at the specified flash offset, which can be
decimal, or hexadecimal with a `0x' prefix). For
instance, to execute the program at offset `0x8000' in
the flash:
echo E0x8000 > /n/rdbg/ctl
The program at the specified offset is expected to have
a standard Plan 9 or AIF header.
The address of a boot parameters structure (see
/os/sa1100/bootparam.h) is passed as the first argument
to the call to the entry routine.
E Execute the default boot program from flash.
eaddress
Execute at the specified memory address.
Soffset
Start at the specified flash offset. A call will actu-
ally be made directly to the specified address. The
address of the BPI structure is still passed as the
first argument.
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STYXMON(10.8) (Strongarm) STYXMON(10.8)
saddress
Start at the specified memory address.
r0 Soft reset (reinitialize).
r1 Hard reset.
raddress
Reset to specified address. This allows replacement
monitor code to be tested. Essentially, this stores a
magic number and the address in registers that survive
the reset, and when the system resets and sees the
magic number, it vectors to the specified address
instead of running the normal monitor initialization.
xval Force the current program to exit with the specified
exit code val. This will return Styxmon to the hangout
state.
bbaud
Set the serial speed to the specified baud rate. This
does not change the current speed, but instead changes
the connection speed used after the device is unmounted
and remounted.
C Console reset. This makes all text in the circular
message buffer act as if it is new, so that the next
read of cons or ctl will display all of it. For
instance, if text was put in the circular message
buffer and then the kernel crashed, the following can
be done to recover the final messages:
echo C > /n/rdbg/ctl
cat /n/rdbg/ctl
Or alternatively:
cat /n/rdbg/cons&
echo C > /n/rdbg/ctl
ctl can also be read, in which case it acts like a
non-blocking form of `cons' (ie, it will return the
latest console output, then end-of-file). In most
cases, it is better to leave `cat /n/rdbg/cons&' run-
ning instead, so that all console output can be seen
when it becomes available. There may be cases, how-
ever, where it is desirable just to capture new output
at specified moments.
EXAMPLES
To initiate a connection to a Styxmon-enabled board:
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STYXMON(10.8) (Strongarm) STYXMON(10.8)
echo b9600 > /dev/eia0ctl
mount -A /dev/eia0 /n/rdbg
To connect at a faster rate:
# first connect at 9600:
echo b9600 > /dev/eia0ctl
mount -A /dev/eia0 /n/rdbg
# tell styxmon what rate to use next time:
echo b38400 > /n/rdbg/ctl
unmount /n/rdbg
# now reconnect at the faster rate:
echo b38400 > /dev/eia0ctl
mount -A /dev/eia0 /n/rdbg
To see the initial styxmon startup message (including memory
size, CPU speed, FIDs opened, etc.) after mounting:
cat /n/rdbg/ctl
The script `/usr/ddk/lib/mashinit' has menus to handle con-
necting, changing the speed, downloading kernels, etc. auto-
matically.
In the styxmon console output, a `*' on a line by itself
means that styxmon has returned from executing a command,
and is now polling for Styx messages.
Styxmon on the SA1100 uses DMA channel 3 to collect data
from the FIFO's of serial port 3. If that serial port is to
be reused for some other purpose, it is important to make
sure that the DMA channel is disabled first.
SEE ALSO
sboot(10.8)
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