Nor Flash maintaince in Linux 2.6

Srinivas G.

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Nov 21, 2006, 7:16:48 AM11/21/06

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Dear Experts,

I am going to port Linux (2.6 kernel) on my ARM development board. And I wanted use NOR flash memory in my development board.

Before porting Linux, I wanted to know whether any tool available on Linux for compacting and maintaining optimal life of my NOR flash?

Any Suggestion is appreciated.

Regards,

Srinivas

Girish Venkatachalam

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Nov 21, 2006, 8:46:46 AM11/21/06

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On Tue, Nov 21, 2006 at 05:46:48PM +0530, Srinivas G. wrote:
> Dear Experts,
>
>
>
> I am going to port Linux (2.6 kernel) on my ARM development board. And I
> wanted use NOR flash memory in my development board.
>
> Before porting Linux, I wanted to know whether any tool available on
> Linux for compacting and maintaining optimal life of my NOR flash?

Hey,
I don't get your question.

You are asking about flash file systems and stuff.. or how to do it?

It is taken care of automagically by file systems like JFFS2 or YFFS.

google for them.

Most estimates on life getting over and all that are bogus.

If you use the right file system it will last long enough.

At least considering the failure rates of hard disk these days, I think it is mostly a non issue.

Another thing. Please don't run swap on NOR flash.

Use ramdisk...

Best,
Girish

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Girish Venkatachalam

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Nov 21, 2006, 9:05:03 AM11/21/06

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On Tue, Nov 21, 2006 at 07:16:46PM +0530, Girish Venkatachalam wrote:
>
> You are asking about flash file systems and stuff.. or how to do it?
>
> It is taken care of automagically by file systems like JFFS2 or YFFS.
>
> google for them.

Oops, I meant YAFS....

>
> Most estimates on life getting over and all that are bogus.
>
> If you use the right file system it will last long enough.
>
> At least considering the failure rates of hard disk these days, I think it is mostly a non issue.
>
> Another thing. Please don't run swap on NOR flash.
>
> Use ramdisk...

Oops! Bummer!

Y wud u have a ramdisk on embedded systems?

Anyway I think I need sleep. :)

regards,

Vijairaj

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Nov 21, 2006, 12:48:03 PM11/21/06

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On 11/21/06, Srinivas G. <srin...@esntechnologies.co.in> wrote:
> Before porting Linux, I wanted to know whether any tool available on
> Linux for compacting and maintaining optimal life of my NOR flash?

Tools can't improve the life of a flash but there are best practices
you can follow to improve the overall lifetime. All hardwares are
expected to fail one day and for flash with limited number of
write/erase cycle bad planning can cause premature demise of the
product:
- Use file systems specifically designed for flash, like JFFS2 - they
distribute write cycles and manage the available space in a better way
than with other file systems.
- NOR chips are XIP capable and can be mapped to be the boot device,
in which case, the first few sectors are used for bootup making them
critical and should not be often erased - You can implement modular
bootup - have a very small and very robust 0th stage boot loader at
the first few sectors. The only job of this stage will be to bootstrap
the 1st stage loader. you can deploy redundant 1st stage loaders.
- You can partition your flash and have different filesystems on them.
For eg: the firmware can be on cramfs and the configurations on jffs2.

--
Vijairaj
http://vijairaj.r.googlepages.com/
http://vijairaj.blogspot.com/