[En-Nut-Discussion] Bootloader

[Hugo Simon]

Hi Dave,

> It sounds like you programmed the BOOTRST fuse. That is the only way I
> know of, where the bootloader is executed before your program. While
> there is nothing wrong with this, the current bootloader is not designed
> to be used this way. I made a function for my project, that executes the
Oops? Not?
But this is the only way to keep the bootloader alive if there goes
something wrong during flashing (wrong image or so). I think a simple idea
could be to extend the current bootloader with a checksum test:
In the bootimage's first bytes should be a checksum of the flash content.
Bootloader reads these bytes and compares it with the current flash. If
there is no difference it does nothing and starts the application. If there
are differences it just works like before.

I didn't try the bootloader now, just read the installation docu. So maybe I
missed some functionality of the current one.

> 1. A specific sequence of keys on the keypad at the right time.
> 2. A specific response from the server it contacts.
> 3. Login with telnet and issue a specific command.
2. and 3. would be a good idea for me. Since my application has no keypad or
something like that I can't use it.

> > 3. DHCP and TFTP server must reside on the same machine
>
> Not true. I know, because I run dhcpd and tftpd on 2 different machines,
> and everything works perfect.
Could you give me a hint how to configure this? Bootloader gets it's image
file name from DHCP I thing. How can I tell it that it should use another
machine for tftp? Since this can become a bit offtopic you can contact me
privately at hugo.simon_at_gmx.de.

> with the current bootloader, is the fact it does not support a local
> gateway (at least that is what I've read, I haven't personally tried
> it), and it only supports UDP, and not TCP. Because of those
That's bad! Is this true (the Gateway thing). UDB isn't bad.

> memory, and program it into the FlashROM. Since the Nut/OS application
> would have to help the bootloader by loading the image into external
But then again you have the problem that the bootloader needs the
application. If there is something wrong with the application it can come to
situations where you cannot remote flash your Ethernut anymore.

> memory, it could be a lot more complex about the image format, and where
> it comes from. For example. the image could be encrypted, or password
> protected on a web or ftp server.
Ok, encryption may be usefull in some times. For now it isn't for me. :-)

Thanks for your answer.

bye
Thorsten