code review 6569068: pkg/runtime: Plan 9: add support for recover() and pani...

src/pkg/runtime/stack.h

 // Copyright 2011 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 /*
 Stack layout parameters.
 Included both by runtime (compiled via 6c) and linkers (compiled via gcc).
 
 The per-goroutine g->stackguard is set to point StackGuard bytes
 above the bottom of the stack.  Each function compares its stack
@@ skipping 42 matching lines @@
  */
 
 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. Used on Windows because
         // it does not use a separate stack.
 #ifdef GOOS_windows
         StackSystem = 512 * sizeof(uintptr),
 #else
+#ifdef GOOS_plan9
+        StackSystem = 512,
+#else
         StackSystem = 0,
-#endif
+#endif  // Plan 9
+#endif  // Windows
 
         // The amount of extra stack to allocate beyond the size
         // needed for the single frame that triggered the split.
         StackExtra = 1024,
 
         // The minimum stack segment size to allocate.
         // If the amount needed for the splitting frame + StackExtra
         // is less than this number, the stack will have this size instead.
         StackMin = 4096,
         FixedStack = StackMin + StackSystem,
@@ skipping 18 matching lines @@
 
         // The maximum number of bytes that a chain of NOSPLIT
         // functions can use.
         StackLimit = StackGuard - StackSystem - StackSmall,
 ········
         // The assumed size of the top-of-stack data block.
         // The actual size can be smaller than this but cannot be larger.
         // Checked in proc.c's runtime.malg.
         StackTop = 72,
 };