Hiya! I have a known working microSD card with my own bbl (Linux 4.20
w/patches) and root filesystem (Alpine Linux). This boots up and works fine,
and is my baseline for preparing a second SD card.
I use the following(ish) script to prepare the new card:
BBL=2E54B353-1271-4842-806F-E436D6AF6985 LINUX=0FC63DAF-8483-4772-8E79-3D69D8477DE4 echo "Partitioning disk..." sgdisk --clear \ --new=1:2048:67583 --change-name=1:bootloader --typecode=1:$BBL \ --new=2:264192: --change-name=2:root --typecode=2:$LINUX \ "$bdev" echo "Writing BBL to disk..." dd if="$bblpath" of="$bdev"1 bs=4096 echo "Preparing filesystem..." mkfs.ext4 "$bdev"2 mount "$bdev"2 /mnt echo "Extracting root..." tar -C /mnt -xpvf "$roottar" sync umount /mnt
Afterwards, I took a dump of the bbl partition from my known working SD card
and compared the SHA to a dump from the new SD card’s bbl partition - and they
match. Examining both disks with gdisk also show that they are apparently
identical, except with respect to the size of the second partition (the new
disk is 128G, the known working disk is 8G).
The new SD card does not boot. The UART shows the serial number of my board and
stops there, not showing the logo baked into my BBL and not booting Linux.