On Wed, 21 Nov 2007, Andi Kleen wrote: > On Wednesday 21 November 2007 02:16:11 Christoph Lameter wrote: > > But one can subtract too... > > The linker cannot subtract (unless you add a new relocation types)
The compiler knows and emits assembly to compensate. > All you need is a 2MB area (16MB is too large if you really > want 16k CPUs someday) somewhere in the -2GB or probably better > in +2GB. Then the linker puts stuff in there and you use > the offsets for referencing relative to %gs. 2MB * 16k = 32GB. Even with 4k cpus we will have 2M * 4k = 8GB both do not fit in the 2GB area. The offset relative to %gs cannot be used if you have a loop and are calculating the addresses for all instances. That is what we are talking about. The CPU_xxx operations that are using the %gs register are fine and are not affected by the changes we are discussing. > Then for all CPUs (including CPU #0) you put the real mapping > somewhere else, copy the reference data there (which also doesn't need > to be on the offset the linker assigned, just on a constant offset > from it somewhere in the normal kernel data) and off you go. Real mapping? We have constant offsets after this patchset. I do not get what you are planning here. > Then the reference data would be initdata and eventually freed. > That is similar to how the current per cpu data works. Yes that is also how the current patchset works. I just do not understand what you want changed. - 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/
