image_types_fsl.bbclass: use a sparse file for sdcard generation

This speeds up the generation of the sdcard and reduces the amount of
space used for it.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Reported-by: "John Passaniti" <jpassaniti@ashly.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/classes/image_types_fsl.bbclass b/classes/image_types_fsl.bbclass
index d9e292c..5d213e5 100644
--- a/classes/image_types_fsl.bbclass
+++ b/classes/image_types_fsl.bbclass
@@ -53,7 +53,8 @@ IMAGE_CMD_sdcard () {
         TMP=${WORKDIR}/tmp
         SDCARD=${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.rootfs.sdcard
 
-        dd if=/dev/zero of=${SDCARD} bs=$(expr 1000 \* 1000) count=${SDCARD_SIZE}
+        # Initialize a sparse file
+        dd if=/dev/zero of=${SDCARD} bs=1 count=0 seek=$(expr 1000 \* 1000 \* ${SDCARD_SIZE})
 
         # Create partition table
         parted -s ${SDCARD} mklabel msdos