Re: Q: Filesystem choice..

[David Woodhouse <dwmw2@infradead.org>]

On Sun, 2004-01-25 at 14:53 -0700, Eric W. Biederman wrote:
> The old papers on jffs2 would make it unacceptable as it reserves
> 5 erase blocks. 

It's got slightly different heuristics now -- a proportion of total
size, plus a proportion of total _blocks_. That was done primarily to
deal with NAND flash, where we need _more_ blocks reserved, but it
should also have helped with small NOR flashes. 

You blatantly don't _need_ to reserve five erase blocks to let you
rewrite the contents of the remaining, erm, one erase block full of
data. You can tune this; it's not a mount option but it's relatively
simple to change in the code.

>  And I don't know if yaffs or yaffs2 is any better.

They're for NAND, not NOR flash.

> In addition boot time is important so it would be ideal if I did not
> to read every byte of the ROM chip to initialize the filesystem.

There have been efforts to improve JFFS2 performance in this respect. It
still reads the _header_ from each node of the file system, but doesn't
actually checksum every node any more.

-- 
dwmw2