From 82dec09bd5098715ddf9cd7d2e4abe87606d5249 Mon Sep 17 00:00:00 2001 From: Mike Frysinger Date: Thu, 10 Sep 2015 16:18:03 -0400 Subject: [PATCH] image_signing: use sparse partition extraction Often the partitions we extract have extra space in them, but the dd utility will still write out the excess zeros. That can mean we write out hundreds of megs of data which could otherwise be skipped. We thus waste a good amount of I/O and storage. For now, only use this flag when extracting a partition to a new file as this should be safe (there's no pre-existing data to clobber/merge). BUG=chromium:530730 TEST=`./signing_unittests.py` passes BRANCH=None Change-Id: Ic32665cf7c38fc0a5efc3f8b227fa8ff408ca9e3 Reviewed-on: https://chromium-review.googlesource.com/299450 Commit-Ready: Mike Frysinger Tested-by: Mike Frysinger Reviewed-by: David Riley --- scripts/image_signing/common_minimal.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/image_signing/common_minimal.sh b/scripts/image_signing/common_minimal.sh index 576d2d8fb6..be3d2adcfc 100644 --- a/scripts/image_signing/common_minimal.sh +++ b/scripts/image_signing/common_minimal.sh @@ -229,7 +229,7 @@ extract_image_partition() { local offset=$(partoffset "$image" "$partnum") local size=$(partsize "$image" "$partnum") dd if=$image of=$output_file bs=512 skip=$offset count=$size \ - conv=notrunc 2>/dev/null + conv=notrunc,sparse 2>/dev/null } # Replace a partition in an image from file