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RE: How much flash?



> Thanks for the info. According to the ptablespec which I haven't
> changed, the size of jffs on /dev/flash2 is 0x50000 (327680) 
> bytes. But
> according to df, I had only 192 1K blocks. Is df wrong?

JFFS reserves 2 blocks (2*64k) for garbage collection.

> 
> I had another question anbout the file system on flash. When 
> I put a new
> image on the board, I also put a few binaries on /mnt/flash. 
> After that,
> /dev/flash2 was about 71% full according to df. I then tried to
> overwrite one of the binaries (~75k) with ftp, but I got a 
> "No space on
> device" error.

That makes sense: (192*(1-0.71)) < 75.

There's no such think as "overwrite" when it comes to flash chips. There's just
write and erase (erase of at least an entire block) so "overwrite" is handled by JFFS.

> I the tried removing the binary with rm, by no 
> space was
> reclaimed. What do I need to do to remove files from /mnt/flash and
> reclaim space?

You shouldn't have to think about that. I think JFFS does GC before the next write,
but I'm not sure about the algorithms (ask on the jffs-dev mailing list or look
at the source code in os/linux/fs/jffs :-).

Best regards
/Jonas