PageOutline = CalypsoRomloader =

The Romloader is a serial bootloader inside the maskrom of the Calypso/lite/plus DBB.

It can be mapped to the reset-vector (0x000000) on the Calypso by pulling the nIBOOT pin to low, and if activated, it checks both UARTs (MODEM and IRDA) for incoming activation commands for a certain amount of time, if nothing is received, it jumps to the application code in the flash memory.BR
If the flash-memory is unprogrammed (checks a few flash locations for that), it stays activated and waits for incoming commands.

So even on devices which use their own bootloader stored inside the flash, it could be activated by pulling nIBOOT low (but which is inaccessible on most phones).

There are currently 3 known variants:

"non-secure"-Romloader on Calypso/lite

The "non-secure" variant, which is used on the Calypso/Calypso lite and which we support with osmocon.
It doesn't require a "key".

It is known to be used by the Motorola W220, BenQ Siemens A38, the OpenMoko devices (Neo 1973 & Freerunner), as well as on many other Calypso phones (LG, Bird).

"secure"-Romloader on Calypso/lite

This one seems to be used on some newer Calypso batches, and is known to be used on the Alcatel VLE5 series.
In order to activate it, you have to send a "key" (which seems to be the first block stored inside the flash).
Basic reverse engineering is done, but nothing working yet, at least we know the "key" for the Alcatel VLE5 phones.

"secure"-Romloader on Calypso plus

This variant is very similar to the one on the Calypso, it requires a key, too, and has some different structure of the branch address.
It also seems to cooperate in some way with a second loader stored inside the flash.
We know the key for the Motorola C261 (which is manufactured by Compal).

Romloader support in osmocon

For downloading code to a romloader target, connect your serial cable as with the Compal devices, start osmocon with the "-m romload" switch, and push the power button shortly.
Osmocon will activate the loader, download the code in blocks, submit a checksum and send a branch command to 0x820000.

For anyone who wants to try this out on an OpenMoko device, use {{{
$ echo 0 >/sys/bus/platform/devices/neo1973-pm-gsm.0/power_on
$ echo 1 >/sys/bus/platform/devices/neo1973-pm-gsm.0/power_on
}}}

to control the GSM Module.

Since the Romloader itself uses 512 Byte of the RAM above 0x800000, we need a different memory layout, but for testing you can use loader.osmoload.bin, which can be loaded to 0x820000.

{{{
$ ./osmocon -p /dev/ttyUSB0 -m romload ../../target/firmware/board/compal_e88/loader.osmoload.bin
}}} * Push the power-on button of your phone (short push, not like a regular phone boot!) * Observe output resembling the following {{{
Sending beacon...
Sending beacon...
Sending beacon...
Sending beacon...
got 1 bytes from modem, data looks like: 3e
got 1 bytes from modem, data looks like: 69
Received ident ack from phone, sending parameter sequence
read_file(../../target/firmware/board/compal_e88/loader.osmoload.bin): file_size=14580, hdr_len=0, dnload_len=14583
Received parameter ack from phone, starting download
Used blocksize for download is 1024 bytes
Preparing block 1, block checksum is 0x93
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 0 finished
Received block ack from phone
Preparing block 2, block checksum is 0x3b
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 1 finished
Received block ack from phone
Preparing block 3, block checksum is 0x79
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 2 finished
Received block ack from phone
Preparing block 4, block checksum is 0x83
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 3 finished
Received block ack from phone
Preparing block 5, block checksum is 0xe5
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 4 finished
Received block ack from phone
Preparing block 6, block checksum is 0x6a
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 5 finished
Received block ack from phone
Preparing block 7, block checksum is 0x98
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 6 finished
Received block ack from phone
Preparing block 8, block checksum is 0x86
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 7 finished
Received block ack from phone
Preparing block 9, block checksum is 0x0f
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 8 finished
Received block ack from phone
Preparing block 10, block checksum is 0xa1
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 9 finished
Received block ack from phone
Preparing block 11, block checksum is 0x07
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 10 finished
Received block ack from phone
Preparing block 12, block checksum is 0x5c
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 11 finished
Received block ack from phone
Preparing block 13, block checksum is 0x68
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 12 finished
Received block ack from phone
Preparing block 14, block checksum is 0x1c
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 13 finished
Received block ack from phone
Preparing the last block, filling 630 bytes, block checksum is 0x54
handle_write_block(): 1024 bytes (1024/1024)
handle_write_block(): Block 14 finished
Finished, sent 14 blocks in total
Received block ack from phone
Sending checksum: 0xdd
Checksum on phone side matches, let's branch to your code
Branching to 0x00820000
Received branch ack, your code is running now!

OSMOCOM Calypso loader (revision 7025e5c-modified) ======================================================================
Running on compal_e88 in environment osmoload

}}}