From eb461485f4558e362fab905735b50987505bca44 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Wed, 11 Jul 2018 09:22:27 +0800 Subject: [PATCH] qemu-img: Document copy offloading implications with -S and -c 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 -- 2.30.2