It looks like there was going to be code to check we had some sort of
alignment so lets replace it with an actual check. This is a bit more
useful than the enigmatic "failed to read the initial flash content"
when we attempt to read the number of bytes the device should have.
This is a potential 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 <alex.ben...@linaro.org>
Reviewed-by: Laszlo Ersek <ler...@redhat.com>
---
v3
- tweak commit title/commentary
- use total_len instead of device_len for checks
- if the device is read-only do the padding for them
- accept baking_len > total_len (how to warn_report with NULL *errp?)
v4
- error check blk_getlength
- optimise memset and use NOR erase pattern
- restore singular device (overly confusing)
- add warn_report for when we do magic
v5
- remove mention of null padding
- use %zu for size_t fmt string
- add Laszlo r-b
---
hw/block/pflash_cfi01.c | 40 +++++++++++++++++++++++++++++++++-------
1 file changed, 33 insertions(+), 7 deletions(-)
diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
index 9d1c356eb6..d8cfa4789a 100644
--- a/hw/block/pflash_cfi01.c
+++ b/hw/block/pflash_cfi01.c
@@ -45,6 +45,7 @@
#include "qemu/bitops.h"
#include "qemu/host-utils.h"
#include "qemu/log.h"
+#include "qemu/error-report.h"
#include "hw/sysbus.h"
#include "sysemu/sysemu.h"
#include "trace.h"
@@ -730,13 +731,6 @@ static void pflash_cfi01_realize(DeviceState *dev, Error
**errp)
}
device_len = sector_len_per_device * blocks_per_device;
- /* XXX: to be fixed */
-#if 0
- if (total_len != (8 * 1024 * 1024) && total_len != (16 * 1024 * 1024) &&
- total_len != (32 * 1024 * 1024) && total_len != (64 * 1024 * 1024))
- return NULL;
-#endif
-
memory_region_init_rom_device(
&pfl->mem, OBJECT(dev),
&pflash_cfi01_ops,
@@ -763,6 +757,38 @@ static void pflash_cfi01_realize(DeviceState *dev, Error
**errp)
}
if (pfl->blk) {
+ /*
+ * Validate the backing store is the right size for pflash
+ * devices. It should be padded to a multiple of the flash
+ * block size. 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) {
+ error_setg(errp, "unable to check size of backing file");
+ return;
+ }
+
+ if (backing_len < total_len) {
+ 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);
+ }
+
/* read the initial flash content */
ret = blk_pread(pfl->blk, 0, pfl->storage, total_len);
--
2.20.1
