Re: Can jffs2 support XIP extensions?

Joshua Wise
2004-08-24T19:10:51Z

> For the kernel boot time it's true that boot times tend to be dominated
> by the decompression step. I measured this on a couple platforms at one
> point (some of my measurements may have been in the OLS presentation,
> not sure). I didn't directly measure kernel boot times of an
> uncompressed non-XIP kernel, but would roughly guess an uncompressed
> non-XIP kernel would boot to /sbin/init in only about a few tens of
> milliseconds more time (I'm guessing about the increased time to copy an
> uncompressed tetx image to RAM) than an XIP kernel on a 266MHz PowerPC
> 405LP, and 168MHz OMAP ARM 926T is probably similar (it seems to better
> deal with the cache effects).
Also remember that on many systems, flash is a lot slower than RAM, so
it is entirely possible that an XIP kernel would actually be _SLOWER_
than non-XIP!

joshua