All tasks structs are 8 kB aligned, which results in very bad cache
behaviour when walking the task chains.

The attached patch moves the task structure into a slab, with normal
cache colouring.
It's tested with i386 SMP.(i.e. it boots and runs X)

'current=%esp&0xffffe000' was replaced with reusing %cr2.

There are 2 changes that might have side effects:

1) arch/i386/kernel/entry.S:
<<<<<<
error_code:
[...]
-       GET_CURRENT(%ebx)
        call *%edi
        addl $8,%esp
+       GET_CURRENT(%ebx)
<<<<<
The pointer to current was loaded into %ebx before the call to the error
handler, now that only happens after the call. As far as I can see the
load before the call is not required.

2) arch/i386/kernel/smpboot.c:
- stack_start.esp = (void *) (1024 + PAGE_SIZE + (char *)idle);
+ stack_start.esp = (void *) (THREAD_SIZE + (char
*)TSK_TO_KSTACK(idle));

I don't understand why the top 3 kB of the stack are not used.

--
	Manfred