On Tue, 10 Jul 2012 16:52:18 +0000, Arnd Bergmann <a...@arndb.de> wrote: > On Tuesday 10 July 2012, Alan Cox wrote: > > > In the AArch32 kernel port many implementation decisions newer > > > architectures were made in a way that preserves backwards compatibility > > > to over 15 years ago (and for good reasons, ARMv4 hardware is still in > > > use). But keeping the same decisions in AArch64 is wrong. > > > > Same argument as x86-32 v x86-64. Same issues about compatibility. > > Similar but not the same. In case of x86-64 the hardware was actually > meant to run old 32 bit kernel binaries and still can. I don't
I know it's a crazy idea, but why don't we try some actual analysis? In 2.5.5, when arch/x86_64 was introduced it was 35412 lines of code. hashmatch (http://www.samba.org/~tridge/hashmatch) says that about 24642 are identical with arch/i386 in the same kernel. That's 70%. Some of that's boilerplate: 9610 lines are in common with arch/sparc64 (27%), so let's say that 43% of x86-64 was specifically sharable with i386. arch/aarch64/ is 22016 line of code. Hashmatch says 12509 (57%) is in common with arch/arm. But only 3232 lines (15%) are in common with sparc. So let's say that 42% of aarch64 is specifically sharable with arm. Looks equivalent to me. They will merge eventually. That said: 1) It's nice to have a clear division of maintainer responsibilities in the near term. 2) PowerPC only "merged" by removing a raft of older platforms, and I don't think ARM is ready for that. And yes, aarch64 is a stupid name. Cheers, Rusty. -- 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/