Mostly costmetic updates

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5452 42af7a65-404d-4744-a932-0658087f49c3

nuttx/arch/sh/src/common/up_doirq.c

@@ -79,6 +79,15 @@ uint32_t *up_doirq(int irq, uint32_t* regs)
     {
        uint32_t *savestate;
 
+       /* Nested interrupts are not supported in this implementation.  If
+        * you want to implement nested interrupts, you would have to (1)
+        * change the way that current_regs is handled and (2) the design
+        * associated with CONFIG_ARCH_INTERRUPTSTACK.  The savestate
+        * variable will not work for that purpose as implemented here
+        * because only the outermost nested interrupt can result in a
+        * context switch (it can probably be deleted).
+        */
+
        /* Current regs non-zero indicates that we are processing
         * an interrupt; current_regs is also used to manage
         * interrupt level context switches.