Skip to main content
After a successful build, the Qualcomm® Linux boot system uses two flashed images to bring up the kernel: efi.bin (ESP partition) and dtb.bin (DTB partition).

​
Image composition

The Yocto build packages kernel artifacts into flashable images:
  • efi.bin is the EFI System Partition (ESP) image. Contains systemd-boot (boot manager) and the kernel packaged as a UKI type-2 image, which bundles the kernel, initramfs, and optionally a device tree. Flashed to the efi partition.
  • dtb.bin is the DTB partition image. Contains all compiled device tree blobs (DTBs). Flashed to the dtb_a partition.
Table: Kernel build artifacts

​
Deploy kernel artifacts

If you have not previously flashed all boot binaries, follow the full flashing instructions in the BSP image build with firmware first. For subsequent kernel-only updates, you can incrementally flash just efi.bin and dtb.bin:
Both efi.bin and dtb.bin must be flashed together after a kernel or DTS change to keep the kernel and device tree in sync.

​
Verify the running kernel

After the device reboots, confirm that the expected kernel version is running and that the boot completed without errors.

​
Connect to the device

Use one of the following methods to access a shell on the device:
  • Serial console (UART) is recommended for early-boot inspection. For setup instructions see Connect to your target.
  • ADB shell once the device has fully booted:
  • SSH to connect over the network using the device IP address:

​
Check the kernel version

The output of uname -r should reflect the kernel version you built and flashed (for example, a 6.18.x string for the LTS track).

​
Inspect boot health

Check the kernel ring buffer for errors or warnings from early boot:
On systems using systemd, kernel messages from the current boot can also be viewed with:

​
Confirm kernel modules

Verify that the expected kernel modules loaded successfully:
To check if a required module is missing, confirm it was included in the kernel configuration and that the image was rebuilt after the configuration change by running following command on target:

​
Troubleshooting

If the kernel version does not match what was built, or if the device fails to boot:
  • Confirm the flash completed without errors by re-running the fastboot flash commands and checking for OKAY responses.
  • Confirm that both efi.bin and dtb.bin were flashed to the correct partitions (efi and dtb_a respectively).
  • For boot failure and kernel panic analysis, see Troubleshoot kernel issues.
  • For serial console log capture, see Kernel logging.