For the IoTKit MPC support, we need to wire together the
interrupt outputs of 17 MPCs; this exceeds the current
value of MAX_OR_LINES. Increase MAX_OR_LINES to 32 (which
should be enough for anyone).
The tricky part is retaining the migration compatibility for
existing OR gates; we add a subsection which is only used
for larger OR gates, and define it such that we can freely
increase MAX_OR_LINES in future (or even move to a dynamically
allocated levels[] array without an upper size limit) without
breaking compatibility.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
include/hw/or-irq.h | 5 ++++-
hw/core/or-irq.c | 39 +++++++++++++++++++++++++++++++++++++--
2 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/include/hw/or-irq.h b/include/hw/or-irq.h
index 3f6fc1b58a4..5a31e5a1881 100644
--- a/include/hw/or-irq.h
+++ b/include/hw/or-irq.h
@@ -31,7 +31,10 @@
#define TYPE_OR_IRQ "or-irq"
-#define MAX_OR_LINES 16
+/* This can safely be increased if necessary without breaking
+ * migration compatibility (as long as it remains greater than 15).
+ */
+#define MAX_OR_LINES 32
typedef struct OrIRQState qemu_or_irq;
diff --git a/hw/core/or-irq.c b/hw/core/or-irq.c
index f9d76c46415..a86901b673c 100644
--- a/hw/core/or-irq.c
+++ b/hw/core/or-irq.c
@@ -66,14 +66,49 @@ static void or_irq_init(Object *obj)
qdev_init_gpio_out(DEVICE(obj), &s->out_irq, 1);
}
+/* The original version of this device had a fixed 16 entries in its
+ * VMState array; devices with more inputs than this need to
+ * migrate the extra lines via a subsection.
+ * The subsection migrates as much of the levels[] array as is needed
+ * (including repeating the first 16 elements), to avoid the awkwardness
+ * of splitting it in two to meet the requirements of VMSTATE_VARRAY_UINT16.
+ */
+#define OLD_MAX_OR_LINES 16
+#if MAX_OR_LINES < OLD_MAX_OR_LINES
+#error MAX_OR_LINES must be at least 16 for migration compatibility
+#endif
+
+static bool vmstate_extras_needed(void *opaque)
+{
+ qemu_or_irq *s = OR_IRQ(opaque);
+
+ return s->num_lines >= OLD_MAX_OR_LINES;
+}
+
+static const VMStateDescription vmstate_or_irq_extras = {
+ .name = "or-irq-extras",
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .needed = vmstate_extras_needed,
+ .fields = (VMStateField[]) {
+ VMSTATE_VARRAY_UINT16_UNSAFE(levels, qemu_or_irq, num_lines, 0,
+ vmstate_info_bool, bool),
+ VMSTATE_END_OF_LIST(),
+ },
+};
+
static const VMStateDescription vmstate_or_irq = {
.name = TYPE_OR_IRQ,
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
- VMSTATE_BOOL_ARRAY(levels, qemu_or_irq, MAX_OR_LINES),
+ VMSTATE_BOOL_SUB_ARRAY(levels, qemu_or_irq, 0, OLD_MAX_OR_LINES),
VMSTATE_END_OF_LIST(),
- }
+ },
+ .subsections = (const VMStateDescription*[]) {
+ &vmstate_or_irq_extras,
+ NULL
+ },
};
static Property or_irq_properties[] = {
--
2.17.1
