Re: JFFS2 mount time

Gareth Bult (Encryptec)
2004-12-17T16:46:13Z

On Fri, 2004-12-17 at 10:02 -0600, Josh Boyer wrote:
> For disk devices I don't think it's required, but it could help. Or
> maybe your code does this at the MTD level. I dunno. I could be
> spouting nonsense again ;).

Mmm, as long as writes are aligned on 2k pages and are linear /
unidirectional, I'm not sure anything else is really a problem
for USB flash drives ..

> Yes, it is a Journaled _Flash_ File System. So of course it's written
> for MTD devices. Not sure why blkmtd.c was originally written. Test
> vehicle for JFFS2, "why not", "I'm bored", etc. Who knows? :)

Mm, my point exactly , Journaled _Flash_ File System - as opposed to
Journaled _MTD_ _Flash_ File System .. !!

USB flash is still flash! - just presented via a generic interface as
opposed to an embedded one .. (AFAIK)

I guess I was sort of hoping blkmtd.c was written to enable JFFS2 to be
more generic and embedded device independent. I suspect however it was
written purely for testing purposes .. :(

As I understand it, the Flash in USB keys is identical to the MTD type
embedded devices, except that the USB keys always come with
micro-controllers that handle and optimise read/write/erase operations
and present them via a generic PC/USB based disk interface. I'm not sure
how fast MTD can be driven, but key manufacturers seem to think that
keys should be able to run at 20Mb/sec read and 10Mb/sec write [for
large block read/writes] which is much faster than is required for a key
to replace a hard disk in a workstation.

I'm thinking that JFFS2 could draw in a huge additional user base if it
catered for (or at least supported) such devices .. (!)

Gareth.