[ECOS] Bootloader capable of writing directly to flash via ymodem serial port download

[Øyvind Harboe <oyvind dot harboe at zylin dot com>]

A while ago I posted an RFC w.r.t. adding support to the
Redboot "load" command for writing directly to flash.

http://sources.redhat.com/ml/ecos-patches/2003-07/msg00023.html

Having gone over the comments, I decided to abandon
the idea in favour of writing a special purpose 
bootloader from scratch.

A scenario where this bootloader makes sense would be:

- the hardware runs a single application that is always
started as soon as the board is powered on
- debugging is handled via a hardware(e.g. JTAG) debugger. No
debug support from eCos.
- much more flash than RAM(e.g. EB40a 2MB flash 256kByte RAM).

This is a short description of the bootloader I wrote:

- It prints a startup message 
- Waits 1 second for \r on the serial port, or it launches
the application. 
- Prints a "are you sure message"
- The user accepts by pressing y
- The area in the flash where the application is stored
is erased
- A ymodem download via serial port is initiated
- The application is written directly to flash
- Once the download is complete the application resets

This bootloader is simply an "eCos ROM application". Similarly the
application is also an "eCos ROM application", but it starts
at the sector after my bootloader.

If there is any interest, I could clean up my code and
submit a draft version of this bootloader to eCos.

Øyvind


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