[PATCH] i386: Use per-cpu GDT immediately upon boot

Now we are no longer dynamically allocating the GDT, we don't need the
"cpu_gdt_table" at all: we can switch straight from "boot_gdt_table" to the
per-cpu GDT.  This means initializing the cpu_gdt array in C.

The boot CPU uses the per-cpu var directly, then in smp_prepare_cpus() it
switches to the per-cpu copy just allocated.  For secondary CPUs, the
early_gdt_descr is set to point directly to their per-cpu copy.

For UP the code is very simple: it keeps using the "per-cpu" GDT as per SMP,
but we never have to move.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/asm-i386/desc.h

@@ -12,8 +12,6 @@
 
 #include <asm/mmu.h>
 
-extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
-
 struct Xgt_desc_struct {
 	unsigned short size;
 	unsigned long address __attribute__((packed));

include/asm-i386/processor.h

@@ -743,7 +743,6 @@ extern unsigned long boot_option_idle_override;
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);
 
-extern void init_gdt(int cpu, struct task_struct *idle);
 extern void cpu_set_gdt(int);
 extern void secondary_cpu_init(void);