Updated the red zone offset to be ABI-compatible and made a more info…

…rmative comment.

sdk/trts/linux/trts_pic.S

@@ -584,13 +584,14 @@ DECLARE_LOCAL_FUNC continue_execution
 
 # do not setup the new stack until info is not needed any more
 # otherwise, info will be overwritten
-# Offset some amount up the stack, to avoid stomping on values in use at the
-# time of the exception.
-    mov     %xcx, -64(%xax)            # save xip to the new stack
+# Offset the stack to avoid the red zone, which interrupts are allowed to
+# write into. Using the __attribute__((interrupt)) on internal_handle_exception
+# is hostile to older compilers.	
+    mov     %xcx, -128(%xax)            # save xip to the new stack
     pop     %xcx                       # restore xcx
     pop     %xsp                       # xsp: xax
     xchg    %xax, %xsp
 
 # The desired xip was stashed further up in the stack; retrieve it and jump
 # there to resume execution.
-    jmp     *-64(%xsp)
+    jmp     *-128(%xsp)