bsps/i386: Interrupt server support

c/src/lib/libbsp/i386/pc386/startup/ldsegs.S

@@ -147,16 +147,16 @@ next_step:
 	outb	al, $0xA1
 	call	SYM(pc386_delay)
 
+	/*
+	 * The IMR values must correspond to the initial value of i8259s_cache.
+	 */
 	movb	$0xFF, al		/* mask off all interrupts for now  */
 	outb	al, $0xA1
 	call	SYM(pc386_delay)
 	movb	$0xFB, al		/* mask all irq's but irq2 which    */
 	outb	al, $0x21		/* is cascaded                      */
 	call	SYM(pc386_delay)
-
+#endif
-	movw	$0xFFFB, SYM(i8259s_cache) /* set up same values in cache */
-
-  #endif
 	jmp	SYM (_establish_stack)	# return to the bsp entry code
 
 /*-------------------------------------------------------------------------+

c/src/lib/libbsp/i386/shared/irq/irq.c

@@ -55,6 +55,7 @@ int      i;
  * This cache is initialized in ldseg.s
  */
 rtems_i8259_masks i8259s_cache = 0xFFFB;
+rtems_i8259_masks i8259s_super_imr = 0xFFFB;
 
 /*-------------------------------------------------------------------------+
 |         Function:  BSP_irq_disable_at_i8259s
@@ -77,6 +78,7 @@ int BSP_irq_disable_at_i8259s    (const rtems_irq_number irqLine)
 
   mask = 1 << irqLine;
   i8259s_cache |= mask;
+  i8259s_super_imr |= mask;
 
   if (irqLine < 8)
   {
@@ -112,6 +114,7 @@ int BSP_irq_enable_at_i8259s    (const rtems_irq_number irqLine)
 
   mask = ~(1 << irqLine);
   i8259s_cache &= mask;
+  i8259s_super_imr &= mask;
 
   if (irqLine < 8)
   {

c/src/lib/libbsp/i386/shared/irq/irq.h

@@ -80,7 +80,19 @@ extern "C" {
  */
 typedef unsigned short rtems_i8259_masks;
 
-extern  rtems_i8259_masks i8259s_cache;
+/**
+ * @brief Contains the current IMR of both i8259s.
+ */
+extern rtems_i8259_masks i8259s_cache;
+
+/**
+ * @brief Contains the super IMR of both i8259s to overrule i8259s_cache during
+ * interrupt exit.
+ *
+ * This enables a bsp_interrupt_vector_disable() in interrupt handlers.  This
+ * is required for the interrupt server support used by the new network stack.
+ */
+extern rtems_i8259_masks i8259s_super_imr;
 
 /*-------------------------------------------------------------------------+
 | Function Prototypes.

c/src/lib/libbsp/i386/shared/irq/irq_asm.S

@@ -214,7 +214,9 @@ nested:
 	cmp       ecx, 16               /* is this a PIC IRQ? */
 	jge       .dont_restore_i8259
 
+	movw      SYM (i8259s_super_imr), dx
 	movl      MSK_OFF(esp), eax
+	orw       dx, ax
 	movw      ax, SYM (i8259s_cache)
 	outb	  $PIC_MASTER_IMR_IO_PORT
 	movb	  ah, al