Re: [ECOS] 2 types of FLASH memory

[Ian Campbell <icampbell at arcom dot com>]

>    a) A long time ago, someone, i forgot who, rewrote the flash
>       infrastructure it make it more plugable. If i remember
>       correctly, that would allow multiple drivers. The contribution
>       never got included, but i cannot remember why. Look back in the
>       ecos-patches archive.

That was me... The problem is that I require a copyright assignment and
management was not happy giving it to Red Hat. They should be more
amenable to assigning it to the FSF and as soon as this is announced I
intend to start pushing to get that signed, post the most recent patches
and begin working in earnest to get them into a state where the
maintainers are happy. I guess I'll extract the patches from our CVS
this afternoon and post them here so that people have something to look
at.

There is also the issue of managing the transition, since a broken flash
driver can render a board rather brick-like. We have been running with
the code for several releases now, but obviously we have only tested on
the hardware we have.

The code is setup such that the old style flash drivers can continue to
work with the new framework, in fact I have only upgraded the
strataflash driver to the new API, we still use AMD flash with the old
driver.

The patches contain a flashdev table infrastructure, and therefore
multiple devices. So far the Red Boot end has not been modified to
support multiple devices.

I have plans for some sort of 'fis select <DEVICE>' command and CDL
options for locating config tables etc in different devices -- they are
just ideas at the moment though. 

>    b) You might not actually need to be able to driver both flashs at
>       the same time. You could build your redboot image to known only
>       about the application flash and your application to know only
>       about your database flash. You need to asses your requirements
>       and see if this is sufficient.

That is what I do at the moment with our AMD + Strataflash board.

Ian.
-- 
Ian Campbell, Senior Design Engineer
                                        Web: http://www.arcom.com
Arcom, Clifton Road, 			Direct: +44 (0)1223 403 465
Cambridge CB1 7EA, United Kingdom	Phone:  +44 (0)1223 411 200


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