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Re: MIPS64EL rootfs available for use and test

On 14 November 2013 18:54, David Daney <ddaney@caviumnetworks.com> wrote:
On 11/14/2013 03:31 AM, Graham Whaley wrote:

Hi David,
  out of interest, do you know if there are any commercially (ideally
easily and cheaply ;-) available boards out there that can run Octeon
little endian?

I don't know...

afaik things like the CN5020 based boards like the
Erlite-3 and CAM-0100 only do big, and afaik there is no (documented)
way to jumper them differently.

On OCTEON, the endianess is under software control, it is *not* a hardware strapping option.  With a suitable bootloader, we still start the system in big endian mode, but if a little-endian ELF image is loaded, we note the endianness, and switch to little endian mode as control is passed to the program entry point.

It has only really been validated on OCTEON II and OCTEON III devices (cn6xxx and cn7xxx).  Certianly the CPU cores on the cn5020 are capable of little endian operation.  The I/O blocks on the other hand have not been validated for little endian operation on that part.

It is known that the bootbus (where the NOR boot flash is connected) has problems in little endian mode on cn5020, so you probably wouldn't be able to use that from Linux.  Also the USB controller on cn5020 has not been adapted and validated for little endian use, so there would be work there.

  My presumption is that the Cavium Octeon devboards from Cavium
themselves (available I believe, but not too cheap) can do both?

As I said above, it is under software control, so any board should be able to do it (given the proper software).

Thanks David - that was all something I'd not come across before with Octeon.
Is this functionality available in any of the open bootloaders (u-boot etc.), or are there any references I can peek at (docs, wiki etc.) ?


David Daney

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