> I'm planning to try porting arcboot to ip27 (mips64). I'm actually doing the same for ip32 (SGI O2). I've added support for 64-bit ELF while sticking to 32-bit arcboot to avoid the issues you mention with 64-bit userland. The code is still a bit ugly and I've hardcoded a different load address for the O2 (this should be a 'configure' option at least), but you might be interested to have a look. The same trick used for the kernel could probably be used to relocate the 32-bit arcboot to 64-bit address space using objcopy, for the ip27 PROM which only supports 64-bit ELF (according to Ralf). An early patch is there: http://www.linux-mips.org/~glaurung/arcboot-0.3.5-o2.diff The idea is to load segments with the KSEG0 version of the physical address, which can be done with 32-bit code (but limits kernel load address to <512Mb). We then jump to the 64-bit entry point with a small bit of mips4 assembly. Comments welcome. Vivien.
