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Re: MCM2+8 with external Flash



On Wed, Oct 22, 2003 at 07:52:58PM +0200, Bernhard Roessmann wrote:
> Hi again,
> 
> I am using a MCM2+8 with 8MByte external flash chip (AMD AM29LV640MT).
> My ptablespec looks like this.
> 
> [ptable]
> # name size     rw-options  type      image-file
> rescue 0x010000 ro          rescue    rescue.img
> flash1 0x1F0000 ro          kernel    flash1.img
> flash2 0x200000 rw          jffs      flash2.img
> 
> As you can see, the whole internal flash (2MB) is used for rescue and 
> flash1, the external flash as flash2 (only 2MB first).
> Everything works fine now.
> 
> If I increase flash2 now up to 0x600000 (6MB), the MCM boots after 
> flashitall and works normally. But it doesn't boot anymore with "normal 
> boot" option (serial kernel output shows nothing!).
> 
> If I increase flash2 beyond 6MB, e.g. 0x800000 (8MB, which ist the 
> external flash size), MCM NEVER boots, neither after the reboot after 
> flashitall nor with normal boot mode.
> 
> 
> Whats wrong?
> 

I'm not sure exactly how RAM is used by the boot loader, but I know that  
it loads the entire flashimage to RAM before writing it to flash. So you 
may need more than 8MB RAM to be able to flash a 6MB image. Maybe 
someone else can explain the bootloader internals?

I suggest that you exclude the jffs-partition from your fimage and 
initialize the jffs partition on first-time boot using eraseflash and dd 
to write an unpadded factorydefault-image /usr/etc/defaultfiles/jimage 
to the character device.

Best regards
/Jonas