Q on MTD support for NOR flash

Q on MTD support for NOR flash

[Kevin Kaichuan He]

Hello,

We are considering to use NOR flash in a embedded linux
system. But it seems that NAND flash support was mentioned
a lot in MTD instead of NOR flash. I'm wondering if there
is intensive NOR flash support in MTD, specifically if
AMD's boot sector NOR flash
(AM29LV800B,http://www.amd.com/us-en/FlashMemory/ProductInformation/0,,37_1447_1623_1468%5E1532,00.html)
is supported.
Also can we partition the AM29LV800B into multiple partitions and
mount different filesystem on it (e.g. JFFS on RW partiton and Cramfs
on RO partition) ? How about the boot sector of NOR flash, is it supported
too ?

Thank you very much for your time!

Kevin


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Re: Q on MTD support for NOR flash

[Jörn Engel]

On Sat, 9 November 2002 12:36:50 -0800, Kevin Kaichuan He wrote:
> 
> We are considering to use NOR flash in a embedded linux
> system. But it seems that NAND flash support was mentioned
> a lot in MTD instead of NOR flash. I'm wondering if there
> is intensive NOR flash support in MTD, specifically if
> AMD's boot sector NOR flash
> (AM29LV800B,http://www.amd.com/us-en/FlashMemory/ProductInformation/0,,37_1447_1623_1468%5E1532,00.html)
> is supported.

Yupp.
Nand flash support is not too old and thus is getting a lot more
development now. Nor, in almost all cases, simply works.

> Also can we partition the AM29LV800B into multiple partitions and
> mount different filesystem on it (e.g. JFFS on RW partiton and Cramfs
> on RO partition) ?

Yupp.

> How about the boot sector of NOR flash, is it supported too ?

Kinda. If you have to access the small fragments seperately, you might
run into problems. But that is usually only done from a bootloader,
not from linux.
For all practical purposes, yupp.

Jörn

-- 
Fancy algorithms are slow when n is small, and n is usually small.
Fancy algorithms have big constants. Until you know that n is
frequently going to be big, don't get fancy.
-- Rob Pike

Re: Q on MTD support for NOR flash

[Kevin Kaichuan He]

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Jorn,

Thank you very much !

One Further question is : how do I configure MTD driver to support
my NOR flash ? For example, the AMD29LV800 flash has two width: 8bits
or 16bits, how do I let the driver know which width of word I choose ?
Or can the MTD magically figure out the configuration of my NOR 
flash ?

thanks!

Kevin

--- Jörn Engel <joern@wohnheim.fh-wedel.de> wrote:
> On Sat, 9 November 2002 12:36:50 -0800, Kevin Kaichuan He wrote:
> > 
> > We are considering to use NOR flash in a embedded linux
> > system. But it seems that NAND flash support was mentioned
> > a lot in MTD instead of NOR flash. I'm wondering if there
> > is intensive NOR flash support in MTD, specifically if
> > AMD's boot sector NOR flash
> >
>
(AM29LV800B,http://www.amd.com/us-en/FlashMemory/ProductInformation/0,,37_1447_1623_1468%5E1532,00.html)
> > is supported.
> 
> Yupp.
> Nand flash support is not too old and thus is getting a lot more
> development now. Nor, in almost all cases, simply works.
> 
> > Also can we partition the AM29LV800B into multiple partitions and
> > mount different filesystem on it (e.g. JFFS on RW partiton and Cramfs
> > on RO partition) ?
> 
> Yupp.
> 
> > How about the boot sector of NOR flash, is it supported too ?
> 
> Kinda. If you have to access the small fragments seperately, you might
> run into problems. But that is usually only done from a bootloader,
> not from linux.
> For all practical purposes, yupp.
> 
> Jörn
> 
> -- 
> Fancy algorithms are slow when n is small, and n is usually small.
> Fancy algorithms have big constants. Until you know that n is
> frequently going to be big, don't get fancy.
> -- Rob Pike


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Re: Q on MTD support for NOR flash

[Jörn Engel]

On Sat, 9 November 2002 23:49:20 -0800, Kevin Kaichuan He wrote:
> 
> One Further question is : how do I configure MTD driver to support
> my NOR flash ? For example, the AMD29LV800 flash has two width: 8bits
> or 16bits, how do I let the driver know which width of word I choose ?
> Or can the MTD magically figure out the configuration of my NOR 
> flash ?

You need something like this:
CONFIG_MTD=y
CONFIG_MTD_PARTITIONS=y
CONFIG_MTD_CHAR=y
CONFIG_MTD_BLOCK=y
CONFIG_MTD_CFI=y
CONFIG_MTD_GEN_PROBE=y
CONFIG_MTD_CFI_AMDSTD=y
CONFIG_MTD_PHYSMAP=y
CONFIG_MTD_PHYSMAP...=...

Details might vary, have fun figuring those out. Buswidth must be set
for physmap.

Jörn

-- 
Good warriors cause others to come to them and do not go to others.
-- Sun Tzu