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-rw-r--r--docs/specs/qcow2.txt7
1 files changed, 6 insertions, 1 deletions
diff --git a/docs/specs/qcow2.txt b/docs/specs/qcow2.txt
index 87bf785fe0..339cdc1b58 100644
--- a/docs/specs/qcow2.txt
+++ b/docs/specs/qcow2.txt
@@ -75,7 +75,12 @@ in the description of a field.
Bitmask of incompatible features. An implementation must
fail to open an image if an unknown bit is set.
- Bits 0-63: Reserved (set to 0)
+ Bit 0: Dirty bit. If this bit is set then refcounts
+ may be inconsistent, make sure to scan L1/L2
+ tables to repair refcounts before accessing the
+ image.
+
+ Bits 1-63: Reserved (set to 0)
80 - 87: compatible_features
Bitmask of compatible features. An implementation can