FTLs for NANDSim

FTLs for NANDSim

[Sun Devil]

Hi  All ...

I'm a newbie to Flash, and actually found NANDSim pretty much
interesting to make my own FTL to interface on to it and measure
several metrics of the existing FTLs too. But, I'm stumped by the fact
that NANDSim runs in Kernel Mode. Can you kindly clarify my following
questions?

1. Can we write an user level FTL and interface with NANDSim, so that,
for the application, simulated flash appears to be a physical device,
and I can format the same volume in what ever way possible?

2. Do you have any implementations of FTL at Kernel level?

3. Are there any NAND Flash simulators that you know of apart from NANDSim?

Thanks a lot!!

Rgds
Sai

Re: FTLs for NANDSim

[David Woodhouse]

On Sat, 2007-10-20 at 09:22 -0700, Sun Devil wrote:
> 1. Can we write an user level FTL and interface with NANDSim, so that,
> for the application, simulated flash appears to be a physical device,
> and I can format the same volume in what ever way possible?

Yes, I suppose you could. You could access the 'flash' through
the /dev/mtd0 character device, then provide a block device to the
kernel by using something like nbd. It's probably better to do it in the
kernel though.

> 2. Do you have any implementations of FTL at Kernel level?

Yes. We have the simplistic 'mtdblock' which doesn't really do any
translation at all, we have 'FTL' which works only on NOR flash, and we
have 'NFTL' and 'INFTL' for use on DiskOnChip devices. There is a helper
layer which is designed to make it relatively easy for you to provide
your own translation layer, without having to get too deeply involved in
how Linux block device drivers work.

> 3. Are there any NAND Flash simulators that you know of apart from NANDSim?

Well, there's a OneNAND sim too. And it's not that hard to use real NAND
flash either -- see Jörn's new 'Alauda' driver for certain USB devices.

-- 
dwmw2

Re: FTLs for NANDSim

[Jörn Engel]

On Mon, 22 October 2007 10:33:08 +0100, David Woodhouse wrote:
> 
> > 2. Do you have any implementations of FTL at Kernel level?
> 
> Yes. We have the simplistic 'mtdblock' which doesn't really do any
> translation at all, we have 'FTL' which works only on NOR flash, and we
> have 'NFTL' and 'INFTL' for use on DiskOnChip devices. There is a helper
> layer which is designed to make it relatively easy for you to provide
> your own translation layer, without having to get too deeply involved in
> how Linux block device drivers work.

There are at least two more:
ssfdc.c
rfd_ftl.c

One of them appears to do the smartmedia format, the other something
very similar.

Jörn

-- 
Science is like sex: sometimes something useful comes out,
but that is not the reason we are doing it.
-- Richard Feynman

Re: FTLs for NANDSim

[Josh Boyer]

On 10/22/07, Jörn Engel <joern@logfs.org> wrote:
> On Mon, 22 October 2007 10:33:08 +0100, David Woodhouse wrote:
> >
> > > 2. Do you have any implementations of FTL at Kernel level?
> >
> > Yes. We have the simplistic 'mtdblock' which doesn't really do any
> > translation at all, we have 'FTL' which works only on NOR flash, and we
> > have 'NFTL' and 'INFTL' for use on DiskOnChip devices. There is a helper
> > layer which is designed to make it relatively easy for you to provide
> > your own translation layer, without having to get too deeply involved in
> > how Linux block device drivers work.
>
> There are at least two more:
> ssfdc.c
> rfd_ftl.c
>
> One of them appears to do the smartmedia format, the other something
> very similar.

There is also UBI of course.  Which people will say isn't an FTL, but
it's somewhat similar.

josh