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Re: Flashing the board from Linux



On Fri, 2003-06-13 at 21:54, Pieter Grimmerink wrote:
> On Friday 13 June 2003 20:03, Uwe Reimann wrote:
> > is it possible to replace the kernel in flash from linux?
> > Like a PC writes it's own bios.
> 
> I think the kernel (as well as the cramsf by the way) run entirely from ram, 
> after bootup.

The kernel yes, but the cramfs is kept in flash and uncompressed (paged
in) to RAM a block at a time on demand.

The old 2.0-NO_MMU (for ETRAX100, not LX) did use a romfs that was
uncompressed to RAM at boot, but the new scheme obviously requires less
RAM.

> I believe there is even an (undocumented?) method to flash the kernel+cramfs 
> image on a running system using sftpd, which is part of the devboard_lx 
> distribution.

Yes, there is. I'm not sure if it is documented anywhere, but see
apps/sftpd/sftpd.c for details. Note you have to be a bit careful
because after you have started to erase the flash you obviously cannot
allow processes to page fault since the cramfs will not be there to page
in from any more... If you want to do your own flash upgrading stuff you
are probably better of starting from the devboard_82 distribution where
the flash upgrade support has been moved to a separate application
(apps/flash) and the FTP-daemon (apps/vftpd) is configured to
communicate with the flash application.

B.t.w., I wouldn't really compare this to rewriting the BIOS, that would
be more like rewriting the rescue partition on the devboard.