On 14 November 2013 18:54, David Daney <dda...@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.) ? Graham > > > David Daney >
