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parallels.txt: fix bitmap L1 table description 

Actually L1 table entry offset is in 512 bytes sectors. Fix the spec.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210224104707.88430-3-vsementsov@virtuozzo.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-02-24 13:47:03 +03:00 committed by Kevin Wolf
parent 35f428ba39
commit 67ae4ace9b
1 changed files with 16 additions and 12 deletions
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28
docs/interop/parallels.txt
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@ -208,21 +208,25 @@ of its data area are:
28 - 31: l1_size
The number of entries in the L1 table of the bitmap.
variable: l1_table (8 * l1_size bytes)
L1 offset table (in bytes)
variable: L1 offset table (l1_table), size: 8 * l1_size bytes
A dirty bitmap is stored using a one-level structure for the mapping to host
clusters - an L1 table.
The dirty bitmap described by this feature extension is stored in a set of
clusters inside the Parallels image file. The offsets of these clusters are
saved in the L1 offset table specified by the feature extension. Each L1 table
entry is a 64 bit integer as described below:
Given an offset in bytes into the bitmap data, the offset in bytes into the
image file can be obtained as follows:
Given an offset in bytes into the bitmap data, corresponding L1 entry is
offset = l1_table[offset / cluster_size] + (offset % cluster_size)
l1_table[offset / cluster_size]
If an L1 table entry is 0, the corresponding cluster of the bitmap is assumed
to be zero.
If an L1 table entry is 0, all bits in the corresponding cluster of the bitmap
are assumed to be 0.
If an L1 table entry is 1, the corresponding cluster of the bitmap is assumed
to have all bits set.
If an L1 table entry is 1, all bits in the corresponding cluster of the bitmap
are assumed to be 1.
If an L1 table entry is not 0 or 1, it allocates a cluster from the data area.
If an L1 table entry is not 0 or 1, it contains the corresponding cluster
offset (in 512b sectors). Given an offset in bytes into the bitmap data the
offset in bytes into the image file can be obtained as follows:
offset = l1_table[offset / cluster_size] * 512 + (offset % cluster_size)