Boot flash

Boot flash

[Joakim Tjernlund]

Hi all

I want to use JFFS on a custom made PPC860 board. This board will have NOR
flash memory(Intel) and will probably use ppcboot(suggestions for better
boot loader welcome).
Can I have ppcboot share a flash device with JFFS?

something like this:

  FLASH device 1:
  -------------------------  address 0
  |  ppcboot              |
  |-----------------------|
  |  linux kernel         |
  |-----------------------|
  |  start of JFFS        |
  |                       |
  |                       |
  |                       |
  |                       |
  -------------------------
  FLASH device 2:
  -------------------------
  |   JFFS continued      |
  |                       |
  |                       |
  |                       |
  |                       |
  |                       |
  |                       |
  |                       |
  |                       |
  -------------------------

ppcboot starts after a reset, loads the linux kernel image. The linux kernel
expects to find JFFS at some offset(compiled into JFFS) in the flash device.

Is this possible or do I need an extra boot flash where ppcboot and linux
kernel goes?

        Jocke



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Re: Boot flash

[David Woodhouse]

joakim.tjernlund@lumentis.se said:
> I want to use JFFS on a custom made PPC860 board. This board will have
> NOR flash memory(Intel) and will probably use ppcboot(suggestions for
> better boot loader welcome). Can I have ppcboot share a flash device
> with JFFS?

Assuming ppcboot is happy with this arrangement, yes. Arrange the 'map'
driver to split the flash into multiple partitions after probing it. See
pnc2000.c for one of many examples of this. The boot partition appears to
the upper layers, including JFFS, as an entirely separate MTD device.

--
dwmw2




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