[U-Boot-Users] MTD Concat support

[Luigi 'Comio' Mantellini <luigi.mantellini@idf-hit.com>]

Hi Vlad and list,

see inline comments.

On mer, 2008-04-16 at 16:05 +0300, Vlad Lungu wrote:
> Luigi 'Comio' Mantellini wrote:
> > .. cut...
> >
> > The answer is pretty simple: the flash layout is a project
> > constraint :D. I know that this approach is very slow, but the target
> > application is a device that should be rebooted about once in a year.
> >   
> 
> Well, it all depends if you really mean loopback or if it is ramdisk. 
> Loopback feels totally wrong unless the rootfs is read-only.

The rootfs will be Read-only. Any write access will be redirected to a
ramdisk. Only during the "upgrading" activity the JFFS2 will be write
from an custom user application, while during the normal activity both
JFFS2 and loopback-mounted Root filesystem will be Read-only.

> Really.
> If it is ramdisk, I guess you could store uImages directly in the NOR 
> flash (one at the beginning, one at the end so you know you can
> easily replace any of them, or if you know that they are <9Mo, 3 of them 
> equally spaced).

I cannot store the uImages in separated memory space...

> 
> Anyway,  back to your original question: if the flash devices are 
> identical and the erase sectors have the same size, you could probably
>  fill flash_info[] yourself instead of auto-detecting and pretend you 
> have a single flash twice the size (i.e. 32Mo). After all, this is NOR
> flash so you're not  actually using sector numbers like with NAND parts. 
> And the addresses are consecutive, so for all intents and purposes,
> it looks like a big flash until you do READ_ID.
> 

Ok. This can be a solution.

thanks

luigi
> Vlad
> 

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