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Re: JFFS2 and XIP



Scott Anderson wrote:

> Vipin Malik wrote:
> > Why? With DRAM < $0.25/MB, you are better off running from RAM anyway.
> > I don't think that there is any platform that Linux runs on that does not support
> > some form of DRAM.
>
> When I asked that question, I was told that FLASH is much lower power
> than RAM so the more you shove into FLASH, the longer the battery life
> can be...

That's questionable- specially the "much lower power" part. (Heck it may even be
higher power during access).
Plus, remember that even DRAM (specially if your system supports things like read
ahead (burst reads) etc.) is going to be significantly faster than FLASH.

Another thing. If your processor has a I-cache (and the trend even in embedded
processors is that they do), your cannot cache the FLASH space as it can change
underneath the OS (things like sector erases are difficult to communicate to the OS).
Most folks just run with the flash not cached. In that case, running out of FLASH will
be *significantly* slower than DRAM.

Just my 2c worth

Vipin



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