[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-block] [RFC PATCH v6 2/4] hw/block: Pad undersized read-only image
From: |
Markus Armbruster |
Subject: |
[Qemu-block] [RFC PATCH v6 2/4] hw/block: Pad undersized read-only images with 0xFF |
Date: |
Thu, 7 Mar 2019 10:37:21 +0100 |
From: Alex Bennée <address@hidden>
We reject undersized images. As of the previous commit, even with a
decent error message. Still, this is a potentially confusing
stumbling block when you move from using -bios to using -drive
if=pflash,file=blob,format=raw,readonly for loading your firmware
code. To mitigate that we automatically pad in the read-only case and
warn the user when we have performed magic to enable things to Just
Work (tm).
Signed-off-by: Alex Bennée <address@hidden>
Reviewed-by: Laszlo Ersek <address@hidden>
Signed-off-by: Markus Armbruster <address@hidden>
---
hw/block/pflash_cfi01.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
index 75ce8ef489..00980316dc 100644
--- a/hw/block/pflash_cfi01.c
+++ b/hw/block/pflash_cfi01.c
@@ -759,8 +759,9 @@ static void pflash_cfi01_realize(DeviceState *dev, Error
**errp)
if (pfl->blk) {
/*
* Validate the backing store is the right size for pflash
- * devices. If the user supplies a larger file we ignore the
- * tail.
+ * devices. If the device is read-only we can elide the check
+ * and just pad the region first. If the user supplies a
+ * larger file we ignore the tail.
*/
int64_t backing_len = blk_getlength(pfl->blk);
if (backing_len < 0) {
@@ -769,10 +770,21 @@ static void pflash_cfi01_realize(DeviceState *dev, Error
**errp)
}
if (backing_len < total_len) {
- error_setg(errp, "device needs %" PRIu64 " bytes, "
- "backing file provides only %" PRIu64 " bytes",
- total_len, backing_len);
- return;
+ if (pfl->ro) {
+ size_t pad_bytes = total_len - backing_len;
+ /* pad with NOR erase pattern */
+ memset((uint8_t *)pfl->storage + backing_len,
+ 0xff, pad_bytes);
+ warn_report("device needs %" PRIu64
+ " bytes, padded with %zu 0xff bytes",
+ total_len, pad_bytes);
+ total_len = backing_len;
+ } else {
+ error_setg(errp, "device needs %" PRIu64 " bytes, "
+ "backing file provides only %" PRIu64 " bytes",
+ total_len, backing_len);
+ return;
+ }
} else if (backing_len > total_len) {
warn_report("device needs %" PRIu64 " bytes, rest ignored",
total_len);
--
2.17.2