On Tuesday 17 July 2012, Christoph Hellwig wrote: > On Sun, Jul 15, 2012 at 07:43:07PM +0000, Arnd Bergmann wrote: > > Yes, I agree that's the best way to handle this. Compared to other > > architectures, I think x86 is the only that allows booting either a > > 32 or 64 bit kernel on the same system. We used to support 32 bit > > kernels on 64 bit PowerMac, but nobody used it and we discontinued > > it long ago. Tile 64 bit is actually incompatible with 32 bit kernels > > at the architecture level and would require a third mode. On sparc, > > parisc and mips, AFAIK we could support 32 bit kernels on 64 bit > > machines, but never did. > > On mips it works just fine. On Sparc I don't think Linux ever did it, > but Solaris did for a long time, as did (IIRC) NetBSD/OpenBSD.
Ah, I didn't know about mips doing that. I also just remembered that s390 supports running 31 bit kernels on all 64 bit machines, but there is no longer official support for that from IBM's side AFAIK. I certainly expect ARM to be similar to powperpc and sparc here, and anyone trying to submit a 32 bit kernel port for a 64 bit platform will have a hard time arguing why that should be accepted into mainline. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/