1 files changed, 8 insertions, 74 deletions
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index a02010013f..ac992a2f1b 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -592,83 +592,17 @@ int32	runtime·chancap(Hchan*);
 
 void	runtime·ifaceE2I(struct InterfaceType*, Eface, Iface*);
 
-/*
- * Stack layout parameters.
- * Known to linkers.
- *
- * The per-goroutine g->stackguard is set to point
- * StackGuard bytes above the bottom of the stack.
- * Each function compares its stack pointer against
- * g->stackguard to check for overflow.  To cut one
- * instruction from the check sequence for functions
- * with tiny frames, the stack is allowed to protrude
- * StackSmall bytes below the stack guard.  Functions
- * with large frames don't bother with the check and
- * always call morestack.  The sequences are
- * (for amd64, others are similar):
- *
- * 	guard = g->stackguard
- * 	frame = function's stack frame size
- * 	argsize = size of function arguments (call + return)
- *
- * 	stack frame size <= StackSmall:
- * 		CMPQ guard, SP
- * 		JHI 3(PC)
- * 		MOVQ m->morearg, $(argsize << 32)
- * 		CALL morestack(SB)
- *
- * 	stack frame size > StackSmall but < StackBig
- * 		LEAQ (frame-StackSmall)(SP), R0
- * 		CMPQ guard, R0
- * 		JHI 3(PC)
- * 		MOVQ m->morearg, $(argsize << 32)
- * 		CALL morestack(SB)
- *
- * 	stack frame size >= StackBig:
- * 		MOVQ m->morearg, $((argsize << 32) | frame)
- * 		CALL morestack(SB)
- *
- * The bottom StackGuard - StackSmall bytes are important:
- * there has to be enough room to execute functions that
- * refuse to check for stack overflow, either because they
- * need to be adjacent to the actual caller's frame (deferproc)
- * or because they handle the imminent stack overflow (morestack).
- *
- * For example, deferproc might call malloc, which does one
- * of the above checks (without allocating a full frame),
- * which might trigger a call to morestack.  This sequence
- * needs to fit in the bottom section of the stack.  On amd64,
- * morestack's frame is 40 bytes, and deferproc's frame is 56 bytes.
- * That fits well within the StackGuard - StackSmall = 128 bytes
- * at the bottom.  There may be other sequences lurking or yet to
- * be written that require more stack.  Morestack checks to make
- * sure the stack has not completely overflowed and should catch
- * such sequences.
- */
 enum
 {
+	// StackSystem is a number of additional bytes to add
+	// to each stack below the usual guard area for OS-specific
+	// purposes like signal handling.
+	// TODO(rsc): This is only for Windows.  Can't Windows use
+	// a separate exception stack like every other operating system?
 #ifdef __WINDOWS__
-	// need enough room in guard area for exception handler.
-	// use larger stacks to compensate for larger stack guard.
-	StackSmall = 256,
-	StackGuard = 2048,
-	StackBig   = 8192,
-	StackExtra = StackGuard,
+	StackSystem = 2048,
 #else
-	// byte offset of stack guard (g->stackguard) above bottom of stack.
-	StackGuard = 256,
-
-	// checked frames are allowed to protrude below the guard by
-	// this many bytes.  this saves an instruction in the checking
-	// sequence when the stack frame is tiny.
-	StackSmall = 128,
-
-	// extra space in the frame (beyond the function for which
-	// the frame is allocated) is assumed not to be much bigger
-	// than this amount.  it may not be used efficiently if it is.
-	StackBig = 4096,
-
-	// extra room over frame size when allocating a stack.
-	StackExtra = 1024,
+	StackSystem = 0,
 #endif
 };
+