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

Message ID 1414096959-14682-26-git-send-email-kwolf@redhat.com
State New
Headers show

Commit Message

Kevin Wolf Oct. 23, 2014, 8:42 p.m. UTC 
From: Max Reitz <mreitz@redhat.com>

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 <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 docs/specs/qcow2.txt | 1 +
 1 file changed, 1 insertion(+)
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Patch

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