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SubjectRe: ANNOUNCE: Mailing list for memory technology devices.
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David.Woodhouse@mvhi.com (David Woodhouse) writes:

> I've just set up a mailing list for discussion of the memory device subsystem
> that I've started to develop for Linux.
>
> To recap on the status:
>
> We have a basic 'mtd' layer which allows us to register low-level physical
> devices. The low-level devices provide simple functionality (read, write,
> erase block), and the mtd glue layer presents this via a character device to
> the user.
>
> On top of this, there can be loaded high-level drivers which attach to these
> devices and provide more sophisticated functionality, such as the FTL
> 'filesystem', which presents a block device to the user.
>
> This model (and a large amount of the code) is 'borrowed' heavily from David
> Hinds' code in the PCMCIA suite.
>
> Currently, we support the following physical devices...:
> 1. Physical memory over and above what the kernel uses.
> 2. M-Systems' ISA Flash disks.
>
> ... and only one high-level driver: the FTL filesystem driver.
>
> We should shortly have low-level drivers for the M-Systems DiskOnChip 2000,
> and I would like to resync with the PCMCIA drivers, so that PCMCIA flash
> devices can use the same MTD system.
>
> In discussion with David Hinds about two years ago, we decided that this system
> should be designed as a replacement for the PCMCIA version, with a view to
> removing the version in the PCMCIA code (just like the PCMCIA code doesn't have
> its own SCSI subsystem, etc). David - I'm not sure if that's still your
> intention - could you venture an opinion on the subject, please?
>
> The code is available from ftp://imladris.mvhi.com/pub/mtd/

I've done this too.
Check out ftp://ftp.signum.se/pub/alex/flash.diff
I did it for an embedded ppc 8xx port, but it's platform independent.
Contains a generic flash layer and specific support for AMD Flash chips.
It also has FTL support.

I've also got some userspace utils for flash handling and ftl
formating/checking. Ask me if you want them.

Here's the annouce i made on linux-ppc:

I've noticed a lot of people on this list seem to use the ppc 8xx port in
embedded systems, running from flash memory. There have been some
questions about it.

Therefore i give you:
ftp://ftp.signum.se/pub/alex/flash.diff

Patches against Linux 2.2.5

The Flash drivers include:
General detection of CFI compliant flash memories.
A general interface for flash-drivers
Specific support for AMD Flash-chips (only tested on Am29LV017B 4x8bib
configuration)
Implemented char device over the flash interface which can read & write
to flash, writing on erase-sector boundaries implies automatic erase,
ioctls exists to force sector erase and to get information about the
chips.

FTL, for flash filesystems:
FTL layer which implements a 512 byte blockdevice with wear-leveling from
the flash-device (or parts of it). This is a modified version of the ftl
code from the pcmcia code (taken with permission).
This can be used to place a normal ext2fs fs in flash. For optimum
performance some modifications to ext2fs whould be done so that it
frees blocks in the ftl layer that are not used by the fs.
Note that there *might* be patent problems using this code in the US.

/ Alex

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