Hi!
linux-embedded-digest schrieb:
> One suggestion to the cracks: what about a kind of 'write filter' as it is
> used with embedded nt? Read data come from the flash/hd and when tried to
> write a file, this file is stored in ram instead of the flash/hd. Subsequent
> reads to that file go to the ram-copy. This leaves the system always in the
> same state when powering up but enables to work on it as if there's a
> writable flash/hd available. No write accesses to flashs, therefore no
> corrupted fs when suddenly powered down. Capable of running a system from a
> read-only device (CDROM...).
I remember a presentation from tuxia (www.tuxia.com) where they introduced
exactly what you describe. They called it "BCL driver" but I didn't find
it on their web page again (just a robust flash fs blah blah).
Unfortunately, they didn't release it as open source as far as I know.
> Beside, one doesn't need to hold the whole root-fs in ram as it is
> done with initrd.
Not true on my opinion. In our system we tried both: root fs is on
flash disk (mounted ro), initrd gets extracted from image while booting
and mounted to /initrd afterwards (theres an option for it but I'm
to lazy to power up the whole thing right now :). In the root fs we
have links e.g. from /var to /initrd/var. Runs fine, survives power
down, although it was a bit of work to set up all the bit and pieces
correctly, like scripts which extract and pack the initrd image. Biggest
hassle is to remember to make the changes in the initrd image
instead of the initrd-based files :)
Walter
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