[Qemu-devel] [PULL 25/32] docs/qcow2: Limit refcount_order to [0, 6]

[Kevin Wolf]

From: Max Reitz <address@hidden>

Specify the upper limit of refcount_order to be 6 (that is,
refcount_bits = 64). Any larger value does not make much sense when all
offsets, sizes, cluster counts etc. "only" have a width of 64 bit as
well, and very large values would be very difficult to support.
Therefore, just cap it at the largest reasonable value.

Suggested-by: Eric Blake <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
 docs/specs/qcow2.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/specs/qcow2.txt b/docs/specs/qcow2.txt
index 0a878aa..121dfc8 100644
--- a/docs/specs/qcow2.txt
+++ b/docs/specs/qcow2.txt
@@ -110,6 +110,7 @@ in the description of a field.
                     in bits: refcount_bits = 1 << refcount_order). For version 
2
                     images, the order is always assumed to be 4
                     (i.e. refcount_bits = 16).
+                    This value may not exceed 6 (i.e. refcount_bits = 64).
 
         100 - 103:  header_length
                     Length of the header structure in bytes. For version 2
-- 
1.8.3.1