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Re: NAND review
- From: Simon Kallweit <simon dot kallweit at intefo dot ch>
- To: Andrew Lunn <andrew at lunn dot ch>
- Cc: Ross Younger <wry at ecoscentric dot com>, "ecos-devel at ecos dot sourceware dot org" <ecos-devel at ecos dot sourceware dot org>
- Date: Wed, 03 Jun 2009 13:52:27 +0200
- Subject: Re: NAND review
- References: <4A126D59.firstname.lastname@example.org> <20090519162853.GA27459@lunn.ch> <20090603085115.GA27508@lunn.ch> <4A264E85.email@example.com> <20090603104817.GC27508@lunn.ch>
Andrew Lunn wrote:
The philosophical question for us all is whether NAND on its own should be
allowed to use malloc, given that a NAND array will probably always be used
in conjunction with a log-structured filesystem which will chew up
comparatively large amounts of RAM (and, of course, RAM is forever getting
cheaper). Is this a corner or even N-dimensional vertex case; will it
necessarily always be the case that a device with NAND flash will have
enough RAM to support it? Do boards with NAND but not much RAM exist, and if
so do we care about them?
The answer is yes. Simon, could you describe your board. From what i
understand you don't have much RAM.
Well yes, our current hardware has 512k on-chip flash, 64k on-chip ram
and 128k external ram. For additional storage we currently have a 4mb
NOR flash, but we're planning on replacing this with a NAND flash so we
can run a tiny filesystem like UFFS. The current software does only use
static memory with the exception of lwIP, which uses fixed memory pools
for dynamic allocation.
For upcoming products we were thinking about getting rid of the external
ram, which would leave us with only 64k. But this certainly would lead
to problems in other areas as well.