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-rw-r--r--block/vhdx.c6
-rw-r--r--qemu-doc.texi6
2 files changed, 9 insertions, 3 deletions
diff --git a/block/vhdx.c b/block/vhdx.c
index bec10bd..46d504c 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1774,7 +1774,7 @@ static int vhdx_create(const char *filename, QemuOpts *opts, Error **errp)
log_size = qemu_opt_get_size_del(opts, VHDX_BLOCK_OPT_LOG_SIZE, 0);
block_size = qemu_opt_get_size_del(opts, VHDX_BLOCK_OPT_BLOCK_SIZE, 0);
type = qemu_opt_get_del(opts, BLOCK_OPT_SUBFMT);
- use_zero_blocks = qemu_opt_get_bool_del(opts, VHDX_BLOCK_OPT_ZERO, false);
+ use_zero_blocks = qemu_opt_get_bool_del(opts, VHDX_BLOCK_OPT_ZERO, true);
if (image_size > VHDX_MAX_IMAGE_SIZE) {
error_setg_errno(errp, EINVAL, "Image size too large; max of 64TB");
@@ -1936,7 +1936,9 @@ static QemuOptsList vhdx_create_opts = {
{
.name = VHDX_BLOCK_OPT_ZERO,
.type = QEMU_OPT_BOOL,
- .help = "Force use of payload blocks of type 'ZERO'. Non-standard."
+ .help = "Force use of payload blocks of type 'ZERO'. "\
+ "Non-standard, but default. Do not set to 'off' when "\
+ "using 'qemu-img convert' with subformat=dynamic."
},
{ NULL }
}
diff --git a/qemu-doc.texi b/qemu-doc.texi
index ad418f8..aabe8df 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -698,7 +698,11 @@ Supported options:
Specifies which VHDX subformat to use. Valid options are
@code{dynamic} (default) and @code{fixed}.
@item block_state_zero
-Force use of payload blocks of type 'ZERO'.
+Force use of payload blocks of type 'ZERO'. Can be set to @code{on} (default)
+or @code{off}. When set to @code{off}, new blocks will be created as
+@code{PAYLOAD_BLOCK_NOT_PRESENT}, which means parsers are free to return
+arbitrary data for those blocks. Do not set to @code{off} when using
+@code{qemu-img convert} with @code{subformat=dynamic}.
@item block_size
Block size; min 1 MB, max 256 MB. 0 means auto-calculate based on image size.
@item log_size
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