From 67ae4ace9bce25d37be8dd97630ed336c29d6b72 Mon Sep 17 00:00:00 2001
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Date: Wed, 24 Feb 2021 13:47:03 +0300
Subject: [PATCH] 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>
---
docs/interop/parallels.txt | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/docs/interop/parallels.txt b/docs/interop/parallels.txt
index f15bf35bd16..bb3fadf3692 100644
--- a/docs/interop/parallels.txt
+++ b/docs/interop/parallels.txt
@@ -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)
--
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