[U-Boot-Users] [PATCH] DataFlash for AT91RM9200DK board

Wolfgang Denk wd at denx.de
Wed Jun 4 13:53:11 CEST 2003

In message <000d01c32a8d$a615aea0$90f59f0a at pc0709> you wrote:
> I'm working with Nicholas on the dataflash driver for U-Boot.
> The dataflash is used to store big amount of data(up to 128 Mbits for the
> AT45DB128).

OK, so my understanding was correct.

> In our case, we use it to store and boot an image of linux(the dataflash
> contains the linux zImage and the ramdisk).
> This dataflash can be used also for a filesystem.

In this case I think we should offer an interface which looks  to the user like mmeory.

Instead of providing separate commands to read and  write  from  such
"memory" I think we should integrate this into the existing code.

For  example,  writing  to  "normal"  flash  memory  is  an  implicit
operation  to the "cp" (copy) command when it detects that the target
address is in flash memory.

The same should be done for dataflash.

OK, with "normal" flash memory we don't  have  to  special-case  read
accesses  like  used  by  "md" or "bootm" commands - where in case of
dataflash such handling will be necessary.

But especially if you boot Linux from dataflash it seems more logical
to me to use "bootm" directly instead of  using  "dataflash  read"  +
"bootm" in separate steps.

Do you t hink tis is feasible?

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
In general, they do what you want, unless you want consistency.
                                    - Larry Wall in the perl man page

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