How to create Debian 10 SD card image

Host Prerequisites

Debian 10 rootfs tarball

Ref. keep the rootfs for future use

Yocto Linux SD card image

e.g. 5720A1AIM20LIV90100_iMX8M_2020-04-03.img

SDIMAGE=5720A1AIM20LIV90100_iMX8M_2020-04-03.img

backup modules and firmware

BACKUPDIR=~/${SDIMAGE%%_*}
mkdir $BACKUPDIR
MNT=~/mnt
mkdir -p $MNT
PL=`fdisk -lu $SDIMAGE | grep "${SDIMAGE}2" | awk '{print $2}'`
sudo mount -o ro,offset=$((PL*512)) $SDIMAGE $MNT
sudo tar zcvf $BACKUPDIR/lib_modules.tgz -C $MNT lib/modules
sudo tar zcvf $BACKUPDIR/lib_firmware.tgz -C $MNT lib/firmware
sudo umount $MNT

Building Procedures

duplicate from Yocto SDcard image

DEBIMAGE=`sed "s/AIM20//; s/LIV/DIV/" <<< ${SDIMAGE%%_*}`_Debian10_base.img
cp $SDIMAGE $DEBIMAGE
mkfs.ext4 -F -E offset=$((PL*512)) $DEBIMAGE

restore rootfs, modules & firmware

sudo mount -o offset=$((PL*512)) $DEBIMAGE $MNT
sudo tar zxvf $ROOTFS.tgz -C $MNT/
sudo tar zxvf $BACKUPDIR/lib_modules.tgz -C $MNT
sudo tar zxvf $BACKUPDIR/lib_firmware.tgz -C $MNT
sudo umount $MNT

SDcard image is ready

write to SD card

sudo dd if=$DEBIMAGE of=${SD_DEVICE} bs=1M conv=fsync status=progress