Implemented lazy FPU state save/restore. In the end mostly ported from NewOS. SMP safe.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@17251 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/arch/x86/arch_cpu.h

@@ -104,12 +104,10 @@ void i386_enter_uspace(addr_t entry, void *args1, void *args2, addr_t ustack_top
 void i386_set_tss_and_kstack(addr_t kstack);
 void i386_switch_stack_and_call(addr_t stack, void (*func)(void *), void *arg);
 void i386_swap_pgdir(addr_t new_pgdir);
-void i386_fsave(void *fpu_state);
+void i386_fnsave(void *fpu_state);
 void i386_fxsave(void *fpu_state);
 void i386_frstor(const void *fpu_state);
 void i386_fxrstor(const void *fpu_state);
-void i386_fsave_swap(void *old_fpu_state, const void *new_fpu_state);
-void i386_fxsave_swap(void *old_fpu_state, const void *new_fpu_state);
 uint32 x86_read_ebp();
 uint32 x86_read_cr0();
 void x86_write_cr0(uint32 value);

headers/private/kernel/cpu.h

@@ -10,6 +10,7 @@
 
 
 #include <smp.h>
+#include <thread.h>
 #include <timer.h>
 #include <boot/kernel_args.h>
 
@@ -24,6 +25,9 @@ typedef union cpu_ent {
 		int preempted;
 		timer quantum_timer;
 
+		// tells which thread's fpu state we hold
+		struct thread *fpu_state_thread;
+
 		// keeping track of CPU activity
 		bigtime_t active_time;
 		bigtime_t last_kernel_time;

headers/private/kernel/thread_types.h

@@ -139,6 +139,7 @@ struct thread {
 	int32			state;
 	int32			next_state;
 	union cpu_ent	*cpu;
+	union cpu_ent	*fpu_cpu;		/* this cpu holds our fpu state */
 
 	sigset_t		sig_pending;
 	sigset_t		sig_block_mask;