Re: [RFC] Advanced XIP File System

From: Jared Hulbert
Date: Wed May 03 2006 - 01:10:59 EST


Accidentally replied just to Josh, sorry. Included what was offline.

From what I recall, XIP of the kernel off of MTD is limited to ARM. I
assume AXFS suffers the same restriction?

I'm fairly certian it won't. I don't see anything in the code (that
we aren't going to remove) that would cause that. All it needs is
direct memory access to the volume. I'll find out soon, I'm trying to
test it on a X86 UML system.

The XIP awareness in the MTD isn't a requirement for XIP, it's a
requirement to XIP from flash you are going to write, erase or
otherwise mess with.

So you're relying on the fact that the underlying flash chip won't
change from the Read Array state? What happens if someone tries to
use AXFS on an MTD partition, which can cover only a portion of a
chip. That is a fairly common occurance for read-only root
filesystems. Other partitions (say JFFS2) on that chip will cause the
chip state to change...

Right. So that is exactly the case XIP Awareness is in the MTD to
fix, and it does so such that AXFS doesn't have to worry about it.
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