Index: /trunk/ccl/lisp-kernel/x86-asmutils64.s
===================================================================
--- /trunk/ccl/lisp-kernel/x86-asmutils64.s	(revision 4979)
+++ /trunk/ccl/lisp-kernel/x86-asmutils64.s	(revision 4980)
@@ -142,4 +142,32 @@
 _exportfn(C(put_vector_registers))
 _endfn				
-			
+	
+        
+        __ifdef([DARWIN_GS_HACK])
+/* Check (in and ugly, non-portale way) to see if %gs is addressing
+   threads data.  If it was, return 0; otherwise, assume that it's
+   addressing a lisp tcr and set %gs to point to the tcr's tcr.osid,
+   then return 1. */
+	
+thread_signature = 0x54485244 /* 'THRD' */
+	
+_exportfn(C(ensure_gs_pthread))
+        __(cmpl $thread_signature,%gs:0)
+        __(movl $0,%eax)
+        __(je 9f)
+        __(movq %gs:tcr.osid,%rdi)
+        __(movl $0x3000003,%eax)
+        __(syscall)
+        __(movl $1,%eax)
+9:      __(ret)
+_endfn
+
+        /* Ensure that %gs addresses the linear address in %rdi */
+        /* This incidentally returns the segment selector .*/
+_exportfn(C(set_gs_address))
+        __(movl $0x3000003,%eax)
+        __(syscall)
+        __(ret)
+_endfn
+        __endif		
 	_endfile