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[Qemu-devel] [PATCH 05/16] block/parallels: support padded Parallels ima
From: |
Denis V. Lunev |
Subject: |
[Qemu-devel] [PATCH 05/16] block/parallels: support padded Parallels images |
Date: |
Mon, 15 Dec 2014 11:27:50 +0300 |
Unfortunately, old guest OSes do not align partitions to page size by
default. This is true for Windows 2003 and Windows XP.
For the time being Parallels was created an optimization for such OSes
in its desktop product. Desktop users are not qualified enough to create
properly aligned installations. Thus Parallels makes a blind guess
on a customer behalf and creates so-called "padded" images if guest
OS type is specified as WinXP, Win2k and Win2k3.
"Padding" is a value which should be added to guest LBA to obtain
sector number inside the image. This results in a shifted images.
0123 offset inside image (in 512 byte sectors)
+-------
+.012 guest data (512 byte sectors)
+-------
The information about this is available in DiskDescriptor.xml ONLY. There
is no such data in the image header.
There share of such images could be evaluated as 6-8% according to the
statistics in my hands.
This patch obtains proper value from XML and applies it on reading.
Signed-off-by: Denis V. Lunev <address@hidden>
Acked-by: Roman Kagan <address@hidden>
Reviewed-by: Jeff Cody <address@hidden>
CC: Kevin Wolf <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
---
block/parallels.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/block/parallels.c b/block/parallels.c
index c22b91b..fedb009 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -63,6 +63,7 @@ typedef struct BDRVParallelsState {
unsigned int tracks;
unsigned int off_multiplier;
+ unsigned int padding;
} BDRVParallelsState;
@@ -235,6 +236,7 @@ static int parallels_open_xml(BlockDriverState *bs, int
flags, Error **errp)
const char *data;
char image_path[PATH_MAX];
Error *local_err = NULL;
+ BDRVParallelsState *s = bs->opaque;
ret = size = bdrv_getlength(bs->file);
if (ret < 0) {
@@ -264,6 +266,19 @@ static int parallels_open_xml(BlockDriverState *bs, int
flags, Error **errp)
if (root == NULL) {
goto fail;
}
+
+ data = xml_get_text(root, "Disk_Parameters", "Padding", NULL);
+ if (data != NULL) {
+ char *endptr;
+ unsigned long pad;
+
+ pad = strtoul(data, &endptr, 0);
+ if ((endptr != NULL && *endptr != '\0') || pad > UINT_MAX) {
+ goto fail;
+ }
+ s->padding = (uint32_t)pad;
+ }
+
image = xml_seek(root, "StorageData", "Storage", "Image", NULL);
data = ""; /* make gcc happy */
for (size = 0; image != NULL; image = image->next) {
@@ -365,6 +380,10 @@ static int64_t seek_to_sector(BlockDriverState *bs,
int64_t sector_num)
static int parallels_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
+ BDRVParallelsState *s = bs->opaque;
+
+ sector_num += s->padding;
+
while (nb_sectors > 0) {
int64_t position = seek_to_sector(bs, sector_num);
if (position >= 0) {
--
1.9.1
- [Qemu-devel] [PATCH v4 0/16] parallels format support improvements, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 07/16] parallels: change copyright information in the image header, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 04/16] iotests: simple parallels XML disk descriptor file test added, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 05/16] block/parallels: support padded Parallels images,
Denis V. Lunev <=
- [Qemu-devel] [PATCH 06/16] iotests: padded parallels image test, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 03/16] iotests, parallels: quote TEST_IMG in 076 test to be path-safe, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 16/16] iotests: testcase parallels image with snapshots, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 02/16] block/parallels: allow to specify DiskDescriptor.xml instead of image file, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 15/16] block/parallels: support read-only parallels snapshots, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 13/16] block/parallels: read disk size from XML if DiskDescriptor.xml is passed, Denis V. Lunev, 2014/12/15