# Troubleshoot using sample logs

The universal asynchronous receiver/transmitter (UART) logs enable you to monitor and debug the data exchanged between the Qualcomm Linux software and a device using a UART interface.

The sample UART logs help you identify the various stages of system bootup. In the event of a crash, you can use these logs to do the following:

- Determine the stage at which the crash occurred
- Gain a high-level understanding of the execution process

- [PBL/XBL log](https://docs.qualcomm.com/doc/80-70030-4/topic/bootloader-logs.html)
The sample primary boot loader/eXtensible Bootloader (PBL/XBL) log indicates the start and end of the PBL and XBL.
- [UEFI log](https://docs.qualcomm.com/doc/80-70030-4/topic/uefi-log.html)
The UEFI log provides information about the start and end of UEFI.
- [Linux log](https://docs.qualcomm.com/doc/80-70030-4/topic/hlos-logging.html)
The sample log signifies the start of the Linux boot process.
- [Capsule update logs](https://docs.qualcomm.com/doc/80-70030-4/topic/capsule-update-logs.html)
The capsule update log provides information about the start and end of the capsule update.

Last Published: Jul 20, 2026

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