6 files changed, 47 insertions, 15 deletions

diff --git a/i386/i386/fpu.c b/i386/i386/fpu.c
index ddf4c8ed..6ee20150 100644
--- a/i386/i386/fpu.c
+++ b/i386/i386/fpu.c
@@ -494,27 +494,52 @@ ASSERT_IPL(SPL0);
  *
  * Use 53-bit precision.
  */
-void fpinit(void)
+static void fpinit(thread_t thread)
 {
 	unsigned short	control;
 
 ASSERT_IPL(SPL0);
 	clear_ts();
 	fninit();
-	fnstcw(&control);
-	control &= ~(FPC_PC|FPC_RC); /* Clear precision & rounding control */
-	control |= (FPC_PC_53 |		/* Set precision */ 
-			FPC_RC_RN | 	/* round-to-nearest */
-			FPC_ZE |	/* Suppress zero-divide */
-			FPC_OE |	/*  and overflow */
-			FPC_UE |	/*  underflow */
-			FPC_IE |	/* Allow NaNQs and +-INF */
-			FPC_DE |	/* Allow denorms as operands  */
-			FPC_PE);	/* No trap for precision loss */
+	if (thread->pcb->init_control) {
+		control = thread->pcb->init_control;
+	}
+	else
+	{
+		fnstcw(&control);
+		control &= ~(FPC_PC|FPC_RC); /* Clear precision & rounding control */
+		control |= (FPC_PC_53 |		/* Set precision */ 
+				FPC_RC_RN | 	/* round-to-nearest */
+				FPC_ZE |	/* Suppress zero-divide */
+				FPC_OE |	/*  and overflow */
+				FPC_UE |	/*  underflow */
+				FPC_IE |	/* Allow NaNQs and +-INF */
+				FPC_DE |	/* Allow denorms as operands  */
+				FPC_PE);	/* No trap for precision loss */
+	}
 	fldcw(control);
 }
 
 /*
+ * Inherit FPU state from a parent to a child, if any
+ */
+void fpinherit(thread_t parent_thread, thread_t thread)
+{
+	pcb_t pcb = parent_thread->pcb;
+	struct i386_fpsave_state *ifps;
+
+	ifps = pcb->ims.ifps;
+	if (ifps) {
+		/* Parent does have a state, inherit it */
+		if (ifps->fp_valid == TRUE)
+			thread->pcb->init_control = ifps->fp_save_state.fp_control;
+		else
+			/* State is in the FPU, fetch from there */
+			fnstcw(&thread->pcb->init_control);
+	}
+}
+
+/*
  * Coprocessor not present.
  */
 void
@@ -778,7 +803,7 @@ ASSERT_IPL(SPL0);
 	    ifps = (struct i386_fpsave_state *) kmem_cache_alloc(&ifps_cache);
 	    memset(ifps, 0, sizeof *ifps);
 	    pcb->ims.ifps = ifps;
-	    fpinit();
+	    fpinit(thread);
 #if 1
 /* 
  * I'm not sure this is needed. Does the fpu regenerate the interrupt in
diff --git a/i386/i386/fpu.h b/i386/i386/fpu.h
index 7bc64388..caade5d4 100644
--- a/i386/i386/fpu.h
+++ b/i386/i386/fpu.h
@@ -125,5 +125,6 @@ extern void fpexterrflt(void);
 extern void fpastintr(void);
 extern void init_fpu(void);
 extern void fpintr(int unit);
+extern void fpinherit(thread_t parent_thread, thread_t thread);
 
 #endif	/* _I386_FPU_H_ */
diff --git a/i386/i386/pcb.c b/i386/i386/pcb.c
index 6b22e4c4..dd2042d8 100644
--- a/i386/i386/pcb.c
+++ b/i386/i386/pcb.c
@@ -376,7 +376,7 @@ void pcb_module_init(void)
 	fpu_module_init();
 }
 
-void pcb_init(thread_t thread)
+void pcb_init(task_t parent_task, thread_t thread)
 {
 	pcb_t		pcb;
 
@@ -406,6 +406,11 @@ void pcb_init(thread_t thread)
 	pcb->iss.efl = EFL_USER_SET;
 
 	thread->pcb = pcb;
+
+	/* This is a new thread for the current task, make it inherit our FPU
+	   state.  */
+	if (parent_task == current_task())
+		fpinherit(current_thread(), thread);
 }
 
 void pcb_terminate(thread_t thread)
diff --git a/i386/i386/pcb.h b/i386/i386/pcb.h
index 708f30d8..cf476942 100644
--- a/i386/i386/pcb.h
+++ b/i386/i386/pcb.h
@@ -31,7 +31,7 @@
 #include <mach/thread_status.h>
 #include <machine/thread.h>
 
-extern void pcb_init (thread_t thread);
+extern void pcb_init (task_t parent_task, thread_t thread);
 
 extern void pcb_terminate (thread_t thread);
 
diff --git a/i386/i386/thread.h b/i386/i386/thread.h
index 35a28025..9bda11f5 100644
--- a/i386/i386/thread.h
+++ b/i386/i386/thread.h
@@ -177,6 +177,7 @@ typedef struct pcb {
 	struct i386_saved_state iss;
 	struct i386_machine_state ims;
 	decl_simple_lock_data(, lock)
+	unsigned short init_control;		/* Initial FPU control to set */
 #ifdef LINUX_DEV
 	void *data;
 #endif /* LINUX_DEV */
diff --git a/kern/thread.c b/kern/thread.c
index d8d6af57..a2ec3d31 100644
--- a/kern/thread.c
+++ b/kern/thread.c
@@ -440,7 +440,7 @@ kern_return_t thread_create(
 	 *	Create a pcb.  The kernel stack is created later,
 	 *	when the thread is swapped-in.
 	 */
-	pcb_init(new_thread);
+	pcb_init(parent_task, new_thread);
 
 	ipc_thread_init(new_thread);