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Subject: Re: Update: Test - Rockbox running directly from flash rom (ROMbox)
From: [IDC]Dragon (idc-dragon_at_gmx.de)
Date: 2004-07-22


> > No risk. It's the same layout as before. But the Rockbox image
> > doesn't get
> > decompressed to RAM and executed there.
> > Instead, it is directly started.
>
> Am I missing something fundamental here?
> Could you please enlighten me (or rather hit me on the head with) how
> this works without first decompressing?

We have 256 KB Flash. My bootloader takes ~2 KB, the compressed Archos image
ranges from 47 KB (Player) over 66 KB (V1) to 77 KB (FM). Behind that, we
have space for our Rockbox image. Because of the flash sectoring, it has to
start at the next 4 KB bounday. The free space is:

Player: 204 KB ( but no flashable Rockbox available)
Recorder V1: 188 KB
Recorder V2: 184 KB
FM: 176 KB

If Rockbox fits in this space without compression, we can run it directly
from flash and save the RAM it would occupy, if it is compiled for that. The
bootloader and the .ucl flash plugin support that since a long time, Jens
picked it up again.

The compression is not mandatory, I "invented" that to make 2 images fit in
there. Archos did descrambling into RAM, but no compression involved.

Jörg

-- 
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