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[v5,5/5] block: lift blocksize property limit to 2 MiB

Message ID 20200526081740.256236-6-rvkagan@yandex-team.ru
State New
Headers show
Series block: widen and check consistency of size-related BlockConf properties | expand

Commit Message

Roman Kagan May 26, 2020, 8:17 a.m. UTC 
Logical and physical block sizes in QEMU are limited to 32 KiB.

This appears unnecessary tight, and we've seen bigger block sizes handy
at times.

Lift the limitation up to 2 MiB which appears to be good enough for
everybody, and matches the qcow2 cluster size limit.

Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
---
v4 -> v5:
- split out into separate patch [Philippe]
- as this patch has changed significantly lose Eric's r-b

 hw/core/qdev-properties.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
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Patch

diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index fd945ce77f..01589e1ad6 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -1206,9 +1206,12 @@  const PropertyInfo qdev_prop_size = {
 /* lower limit is sector size */
 #define MIN_BLOCK_SIZE          512
 #define MIN_BLOCK_SIZE_STR      "512 B"
-/* upper limit is the max power of 2 that fits in uint16_t */
-#define MAX_BLOCK_SIZE          (32 * KiB)
-#define MAX_BLOCK_SIZE_STR      "32 KiB"
+/*
+ * upper limit is arbitrary, 2 MiB looks sufficient for all sensible uses, and
+ * matches qcow2 cluster size limit
+ */
+#define MAX_BLOCK_SIZE          (2 * MiB)
+#define MAX_BLOCK_SIZE_STR      "2 MiB"
 
 static void set_blocksize(Object *obj, Visitor *v, const char *name,
                           void *opaque, Error **errp)