From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56690) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fdeVg-0004cS-Jn for qemu-devel@nongnu.org; Thu, 12 Jul 2018 12:32:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fdeVf-00063b-O4 for qemu-devel@nongnu.org; Thu, 12 Jul 2018 12:32:04 -0400 From: Kevin Wolf Date: Thu, 12 Jul 2018 18:31:48 +0200 Message-Id: <20180712163152.12521-4-kwolf@redhat.com> In-Reply-To: <20180712163152.12521-1-kwolf@redhat.com> References: <20180712163152.12521-1-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 3/7] qemu-img: Document copy offloading implications with -S and -c List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org From: Fam Zheng Explicitly enabling zero detection or compression suppresses copy offloading during convert. Document it. Suggested-by: Kevin Wolf Signed-off-by: Fam Zheng Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- qemu-img.texi | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/qemu-img.texi b/qemu-img.texi index aeb1b9e66c..5853cd18d1 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -96,7 +96,8 @@ will enumerate information about backing files in a disk image chain. Refer below for further description. @item -c -indicates that target image must be compressed (qcow format only) +indicates that target image must be compressed (qcow format only). If this +option is used, copy offloading will not be attempted. @item -h with or without a command shows help and lists the supported formats @@ -115,7 +116,8 @@ in case both @var{-q} and @var{-p} options are used. indicates the consecutive number of bytes that must contain only zeros for qemu-img to create a sparse image during conversion. This value is rounded down to the nearest 512 bytes. You may use the common size suffixes like -@code{k} for kilobytes. +@code{k} for kilobytes. If this option is used, copy offloading will not be +attempted. @item -t @var{cache} specifies the cache mode that should be used with the (destination) file. See -- 2.13.6