On Thu, Jul 12, 2007 at 02:18:07AM +0200, Ingo Molnar wrote: > > > i dont think "clean, modern x86 code" will ever happen - x86_64 has > > > and is going to have the exact same type of crap. And i'll say a > > > weird thing > > > > Yes, but it will be new crap, but no old crap anymore. > > > > If you always pile the new crap on the old crap at some point the > > whole thing might fall over. 64bit was intended as a fresh start. > > I think there's no such thing as a fresh start for a diverse > architecture - the ia64 failure has proven that. x86_64 CPUs still do > A20 emulation today (!).
x86-64 doesn't care about a lot of x86 baggage and a lot of things have been even obsoleted in the platform. In practice the backwards compatibility on x86 isn't that great either. For example a significant number of new systems don't even work correctly in PIC mode anymore. > We still have people running industrial boards > on real i386 DX CPUs, with the latest upstream kernel. 15 years ago an Yes, but those for example would be perfectly happy with an arch/i386 with all APIC and SMP code stripped out. Only the few people who still run dual P5s might not, but those could continue using old kernels. But eventually I think that would be the right clean way: arch/i386 stripped down port for truly old systems like the embedded 386 upto 586 or early 686. No SMP or APIC. arch/x86 supporting 32bit and 64bit for reasonably modern systems. NUMAQ/Voyager/P5-SMP/visual workstation gone [frankly the user base of those is too small to justify the code impact] It's just quite ugly to get there and when you think through it the actual advantages of such a setup it is likely not enough to justify the significant work to make it work. Also I wouldn't have any idea how to regression test significant changes to arch/i386 aimed at old systems. e.g. I don't think the powerpc people actually tried to still support really old systems where it is hard to do regression tests anymore, only really supported platforms. So while such a setup would be quite nice the practical problems of getting there are nasty. Also I must admit I prefer hacking on new code instead. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
