From: Josh Boyer <jdub@us.ibm.com>
To: "Gareth Bult (Encryptec)" <Gareth@Encryptec.net>
Cc: Linux MTD <linux-mtd@lists.infradead.org>
Subject: Re: JFFS2 mount time
Date: Fri, 17 Dec 2004 11:10:31 -0600 [thread overview]
Message-ID: <41C31307.70909@us.ibm.com> (raw)
In-Reply-To: <1103302002.15927.198.camel@squizzey.bult.co.uk>
Gareth Bult (Encryptec) wrote:
>
> 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)
No, it's really not. There is no access to the low level flash, so MTD
cannot directly drive it. Same principle as the Compact Flash devices,
which MTD doesn't deal with either (other than via blkmtd).
>
> 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 .. :(
Yes, most likely.
>
> 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.
The flash used in the devices is identical, but MTD has no access to it.
>
> I'm thinking that JFFS2 could draw in a huge additional user base if it
> catered for (or at least supported) such devices .. (!)
That's the problem. There is no filesystem for these "abominations"
really. They pretend to be IDE, SCSI, etc. but are really flash
underneath. Neither the MTD driver or the IDE drivers (for example)
deal with them really well, but I'm not sure that they can.
Did you try ext3 on the device with a native driver (IDE, SCSI, USB
specific) instead of via blkmtd.c?
josh
next prev parent reply other threads:[~2004-12-17 17:10 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-15 23:19 JFFS2 mount time Gareth Bult (Encryptec)
2004-12-16 0:15 ` Josh Boyer
2004-12-16 1:02 ` Gareth Bult (Encryptec)
2004-12-16 12:53 ` Josh Boyer
2004-12-16 21:22 ` Gareth Bult (Encryptec)
2004-12-16 21:28 ` Josh Boyer
2004-12-16 21:47 ` Gareth Bult (Encryptec)
2004-12-17 12:54 ` Josh Boyer
2004-12-17 15:33 ` Gareth Bult (Encryptec)
2004-12-17 16:02 ` Josh Boyer
2004-12-17 16:46 ` Gareth Bult (Encryptec)
2004-12-17 17:08 ` Artem B. Bityuckiy
2004-12-17 17:10 ` Josh Boyer [this message]
2004-12-17 17:26 ` Gareth Bult (Encryptec)
2004-12-17 17:35 ` Josh Boyer
2004-12-17 18:09 ` Gareth Bult (Encryptec)
2004-12-17 19:14 ` jasmine
2004-12-17 20:55 ` Gareth Bult (Encryptec)
2004-12-18 16:02 ` Jörn Engel
2004-12-20 16:34 ` Josh Boyer
2004-12-20 17:12 ` Gareth Bult (Encryptec)
2004-12-21 13:09 ` Jörn Engel
2004-12-21 13:24 ` Gareth Bult (Encryptec)
2004-12-21 13:34 ` Jörn Engel
2004-12-18 16:19 ` Jörn Engel
2004-12-18 17:32 ` Gareth Bult (Encryptec)
2004-12-18 17:52 ` Jörn Engel
2004-12-18 18:11 ` Jörn Engel
2004-12-18 20:48 ` Gareth Bult (Encryptec)
2004-12-19 2:44 ` Jörn Engel
2004-12-21 13:30 ` Jörn Engel
2004-12-21 13:39 ` [PATCH 1/22] Add drivers/mtd/devices/blockmtd.c Jörn Engel
2004-12-21 13:41 ` [PATCH 2/22] Add copyrights Jörn Engel
2004-12-21 13:42 ` [PATCH 3/22] Remove read-only option Jörn Engel
2004-12-21 13:44 ` [PATCH 4/22] Change init/exit functions Jörn Engel
2004-12-21 13:45 ` [PATCH 5/22] Remove gcc warnings Jörn Engel
2004-12-21 13:47 ` [PATCH 6/22] Remove debug macros Jörn Engel
2004-12-21 13:48 ` [PATCH 7/22] Lindent Jörn Engel
2004-12-21 13:49 ` [PATCH 8/22] Remove sync interface Jörn Engel
2004-12-21 13:51 ` [PATCH 9/22] Change parameter interface to phram-style Jörn Engel
2004-12-21 13:53 ` [PATCH 10/22] Cleanup macro usage Jörn Engel
2004-12-21 13:54 ` [PATCH 11/22] kfree simplifications Jörn Engel
2004-12-21 13:55 ` [PATCH 12/22] change blockmtd_sync Jörn Engel
2004-12-21 13:57 ` [PATCH 13/22] remove erase regions Jörn Engel
2004-12-21 14:01 ` [PATCH 14/22] Change add_device Jörn Engel
2004-12-21 14:02 ` [PATCH 15/22] Rename unreadable mutex Jörn Engel
2004-12-21 14:03 ` [PATCH 16/22] list changes Jörn Engel
2004-12-21 14:04 ` [PATCH 17/22] Rename central struct Jörn Engel
2004-12-21 14:06 ` [PATCH 18/22] Function renaming Jörn Engel
2004-12-21 14:09 ` [PATCH 19/22] Fold various erase functions Jörn Engel
2004-12-21 14:10 ` [PATCH 20/22] Fold various write functions Jörn Engel
2004-12-21 14:11 ` [PATCH 21/22] Default erase size Jörn Engel
2004-12-21 14:13 ` [PATCH 22/22] Readahead Jörn Engel
2004-12-21 18:42 ` [PATCH 13/22] remove erase regions Christopher Hoover
2004-12-21 18:49 ` Jörn Engel
2004-12-21 21:09 ` Christopher Hoover
2004-12-22 2:47 ` Eric W. Biederman
2004-12-22 8:59 ` Jörn Engel
2004-12-22 10:05 ` Eric W. Biederman
2004-12-22 10:41 ` Jörn Engel
2004-12-21 13:42 ` [PATCH 1/22] Add drivers/mtd/devices/blockmtd.c Gareth Bult (Encryptec)
2004-12-21 14:15 ` Jörn Engel
2004-12-21 13:40 ` JFFS2 mount time Gareth Bult (Encryptec)
2004-12-21 15:00 ` David Woodhouse
[not found] ` <1103644945.10792.175.camel@squizzey.bult.co.uk>
2004-12-21 16:04 ` Jörn Engel
2004-12-16 13:43 ` Ferenc Havasi
2004-12-20 16:01 ` Gareth Bult (Encryptec)
2004-12-20 16:09 ` Ferenc Havasi
2004-12-20 16:39 ` Gareth Bult (Encryptec)
2004-12-20 17:48 ` Gareth Bult (Encryptec)
-- strict thread matches above, loose matches on Subject: below --
2004-10-20 14:26 Ferenc Havasi
2004-10-20 15:26 ` [OBORONA-SPAM] " Artem B. Bityuckiy
2004-10-20 15:49 ` Ferenc Havasi
2004-10-20 15:53 ` Artem B. Bityuckiy
2004-10-21 6:29 ` Artem B. Bityuckiy
2004-10-21 6:54 ` Ferenc Havasi
2004-10-21 7:16 ` Artem B. Bityuckiy
2004-10-21 19:50 ` Ferenc Havasi
2004-10-21 12:49 ` Jarkko Lavinen
2004-10-21 19:11 ` Ferenc Havasi
2004-10-22 9:58 ` Ferenc Havasi
2004-10-21 13:24 ` David Woodhouse
2004-10-21 20:05 ` Ferenc Havasi
2004-10-22 12:44 ` Artem Bityuckiy
2004-10-25 9:36 ` Ferenc Havasi
2004-10-25 10:56 ` Artem Bityuckiy
2004-10-25 15:30 ` Ferenc Havasi
2004-10-26 9:59 ` Artem Bityuckiy
2004-10-26 10:21 ` Ferenc Havasi
2004-10-26 11:05 ` Artem Bityuckiy
2004-10-26 13:52 ` Ferenc Havasi
2004-10-25 11:21 ` Artem Bityuckiy
2004-10-26 9:29 ` Jarkko Lavinen
2004-10-26 10:24 ` Ferenc Havasi
2004-10-26 10:34 ` Artem Bityuckiy
2004-01-13 12:50 Jarkko Lavinen (NMP/Helsinki)
2004-01-13 13:19 ` Joakim Tjernlund
2004-01-13 13:39 ` David Woodhouse
2004-01-13 15:25 ` Kenneth Johansson
2004-01-13 15:30 ` David Woodhouse
2004-01-13 16:21 ` Kenneth Johansson
2004-01-13 17:29 ` Jörn Engel
2004-01-13 17:40 ` Kenneth Johansson
2004-01-13 18:43 ` Jörn Engel
2005-01-04 15:00 ` Steven Scholz
2005-01-05 10:45 ` Artem B. Bityuckiy
2005-01-05 11:10 ` Ferenc Havasi
2005-01-05 11:24 ` Steven Scholz
2005-01-05 11:45 ` Artem B. Bityuckiy
2005-01-06 10:50 ` Ferenc Havasi
2005-01-10 15:14 ` Steven Scholz
2005-01-10 15:25 ` Steven Scholz
2005-01-11 8:26 ` Ferenc Havasi
2005-01-11 8:34 ` Steven Scholz
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