Re: Strange behavior with I2C on Sequoia board

On Thursday 21 August 2008, Valentine Barshak wrote:

quoted

It seems that your bootwrapper is somehow not copying the correct MAC
address to the device-tree. Not sure what's going wrong here. We usually
don't use the bootwrapper but boot the uImage directly from U-Boot on all
4xx systems.

You might want to debug the bootwrapper code, if possible drop the
bootwrapper and use the uImage with a newer, device-tree enabled U-Boot
version.

U-boot thinks that all memory above the first 8MB is out of reach for
the kernel and puts kernel bootargs and boardinfo structure below 8MB as
close as possible to this limit. Including the i2c driver into the
kernel increases the kernel image size. So when u-boot unpacks the
kernel to 0x400000 (Load Address: 00400000) it overwrites the kernel
parameters. So when the kernel actually starts, it reads zeros instead
of boardinfo (and mac addresses)

The 8MB limit is set for all AMCC boards in include/configs/amcc-common.h:
#define CFG_BOOTMAPSZ		(8 << 20) /* Initial Memory map for Linux */

I think this limit is obsolete and can be moved to at least 64MB.
But you'll need to rebuild u-boot.

Stefan, what do you think? Can we increase the default initial memory
map for AMCC boards in the next u-boot release, since u-boot has all
memory identity-mapped on ppc 44x?

Yes, it was our intention to increase the default map to a higher value a few 
weeks ago. I just forgot to really do it. I'll do this shortly.

Thanks.

Best regards,
Stefan

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