Template:Debian Create Bootable SD
Extending the SD Card Size
Flashing the default img.zst images from Flexbuild results in a rootfs that does not utilize the entire SD card. This section explains how the SD card can be extended on the build host after flashing.
Procedure:
Begin with an SD card on which you have previously flashed a Flexbuild img.zst image. Ensure the SD card is inserted and the device present (i.e. /dev/sda, /dev/mmcblk0, etc.)
Start by running fdisk as below and typing "p" and enter to print current partitions. You should see a layout similar to below but numbers may differ depending on card sizes. Note that the partition starts at 16,384 (bytes offset 16384*512) which is to account for the boot content explained above.
$ sudo fdisk /dev/sdX
Welcome to fdisk (util-linux 2.37.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/sdX: 59.48 GiB, 63864569856 bytes, 124735488 sectors
Disk model: MassStorageClass
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x5ebf1617
Device Boot Start End Sectors Size Id Type
/dev/sdX1 16384 15165439 15149056 7.2G 83 Linux
Next, run the following sequence of commands followed by enter with each step explained with a "-" to the right. Each command/input should be followed by enter:
- d - Delete current partition (1).
- n - Create a new parition.
- - Empty, hit enter only which will leave default response p for primary partition.
- - Empty, hit enter only which will leave default response 1 for first partition.
- 16384 - Enter 16384 to begin partition past bootloader section.
- - Empty, hit enter only which will leave last sector as default which should choose ending size of the SD card.
- N - Answers no to not remove the ext4 signature on the disk
- p - Print output and verify before we write. We should see the starting offset the same and the end expanded to fill the SD card.
- w - Write output to disk
See the full log of the above sequence below:
Command (m for help): d
Selected partition 1
Partition 1 has been deleted.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p):
Using default response p.
Partition number (1-4, default 1):
First sector (2048-124735487, default 2048): 16384
Last sector, +/-sectors or +/-size{K,M,G,T,P} (16384-124735487, default 124735487):
Created a new partition 1 of type 'Linux' and of size 59.5 GiB.
Partition #1 contains a ext4 signature.
Do you want to remove the signature? [Y]es/[N]o: N
Command (m for help): p
Disk /dev/sdX: 59.48 GiB, 63864569856 bytes, 124735488 sectors
Disk model: MassStorageClass
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
identifier: 0x5ebf1617
Device Boot Start End Sectors Size Id Type
/dev/sdX1 16384 124735487 124719104 59.5G 83 Linux
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
Finally, the file system needs to be resized on the disk to fill the now larger partition. Do that as follows:
$ sudo e2fsck -f /dev/sdX1 e2fsck 1.46.5 (30-Dec-2021) root: recovering journal Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information root: 43155/947488 files (0.1% non-contiguous), 674097/1893632 blocks $ sudo resize2fs /dev/sdX1 resize2fs 1.46.5 (30-Dec-2021) Resizing the filesystem on /dev/sdX1 to 15589888 (4k) blocks. The filesystem on /dev/sdX1 is now 15589888 (4k) blocks long. $ sync
Again, numbers and output should differ slightly depending on your card.
Your rootfs image should now fill the entire SD card and is ready to boot.