isr_tables: Support hardware interrupt vector table-only configuration.

The existing isr_tables implementation does not allow enabling only
hardware interrupt vector table without software isr table.

This commit ensures that CONFIG_GEN_IRQ_VECTOR_TABLE can be used
without setting CONFIG_GEN_SW_ISR_TABLE.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

arch/common/isr_tables.c

@@ -29,20 +29,31 @@ Z_GENERIC_SECTION(.irq_info) struct int_list_header _iheader = {
 /* These are placeholder tables. They will be replaced by the real tables
  * generated by gen_isr_tables.py.
  *
- * z_irq_spurious and _isr_wrapper are used as placeholder values to
- * ensure that they are not optimized out in the first link. The first
- * link must contain the same symbols as the second one for the code
- * generation to work.
+ * z_irq_spurious is used as a placeholder value to ensure that it is not
+ * optimized out in the first linker pass. The first linker pass must contain
+ * the same symbols as the second linker pass for the code generation to work.
  */
 
 /* Some arches don't use a vector table, they have a common exception entry
  * point for all interrupts. Don't generate a table in this case.
  */
 #ifdef CONFIG_GEN_IRQ_VECTOR_TABLE
+/* When both the IRQ vector table and the software ISR table are used, populate
+ * the IRQ vector table with the common software ISR by default, such that all
+ * indirect interrupt vectors are handled using the software ISR table;
+ * otherwise, populate the IRQ vector table with z_irq_spurious so that all
+ * un-connected IRQ vectors end up in the spurious IRQ handler.
+ */
+#ifdef CONFIG_GEN_SW_ISR_TABLE
+#define IRQ_VECTOR_TABLE_DEFAULT_ISR	_isr_wrapper
+#else
+#define IRQ_VECTOR_TABLE_DEFAULT_ISR	z_irq_spurious
+#endif /* CONFIG_GEN_SW_ISR_TABLE */
+
 u32_t __irq_vector_table _irq_vector_table[IRQ_TABLE_SIZE] = {
-	[0 ...(IRQ_TABLE_SIZE - 1)] = (u32_t)&_isr_wrapper,
+	[0 ...(IRQ_TABLE_SIZE - 1)] = (u32_t)&IRQ_VECTOR_TABLE_DEFAULT_ISR,
 };
-#endif
+#endif /* CONFIG_GEN_IRQ_VECTOR_TABLE */
 
 /* If there are no interrupts at all, or all interrupts are of the 'direct'
  * type and bypass the _sw_isr_table, then do not generate one.

include/linker/common-ram.ld

@@ -5,7 +5,7 @@
 		DEVICE_INIT_SECTIONS()
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 
-#if defined(CONFIG_GEN_ISR_TABLES) && defined(CONFIG_DYNAMIC_INTERRUPTS)
+#if defined(CONFIG_GEN_SW_ISR_TABLE) && defined(CONFIG_DYNAMIC_INTERRUPTS)
 	SECTION_DATA_PROLOGUE(sw_isr_table,,)
 	{
 		/*

include/linker/common-rom.ld

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: Apache-2.0 */
 
-#if defined(CONFIG_GEN_ISR_TABLES) && !defined(CONFIG_DYNAMIC_INTERRUPTS)
+#if defined(CONFIG_GEN_SW_ISR_TABLE) && !defined(CONFIG_DYNAMIC_INTERRUPTS)
 	SECTION_PROLOGUE(sw_isr_table,,)
 	{
 		/*