# QCC730 boot flow Source: [https://docs.qualcomm.com/doc/80-Y8730-2/topic/qcc730_boot_flow.html](https://docs.qualcomm.com/doc/80-Y8730-2/topic/qcc730_boot_flow.html) QCC730 boot sequence can be divided into two relatively-independent stages: - From PBL to SBL - From SBL to APP ## From PBL to SBL Source: [https://docs.qualcomm.com/doc/80-Y8730-2/topic/qcc730_boot_flow.html](https://docs.qualcomm.com/doc/80-Y8730-2/topic/qcc730_boot_flow.html) This is the first boot stage, which loads and executes the SBL. The PBL performs the following jobs after power-up: 1. Apply PBL patch if it exists 2. Initialize system resource 3. Check boot reason then handle 4. Read FDT to choose SBL image 5. Authenticate SBL image 6. Load image to RAM 7. Load PBL PATCH segment 8. Verify the hash of each image segment 9. Jump to SBL Note: In the above nine steps, - Step 5 is skipped if the boot is a warm boot. - Step 7 is skipped if this isn't an OTA new image. Figure : QCC730 boot sequence: PBL to SBL PBL start PBL start Apply PBL patch Apply PBL patch System init System init Boot reason handle Boot reason handle Read FDT, choose SBL Read FDT, choose SBL Cold boot? Cold boot? Authenticate SBL Authenticate SBL Load SBL to RAM Load SBL to RAM Hash verification Hash verification Execute SBL Execute SBL No No Yes Yes ## From SBL to APP Source: [https://docs.qualcomm.com/doc/80-Y8730-2/topic/qcc730_boot_flow.html](https://docs.qualcomm.com/doc/80-Y8730-2/topic/qcc730_boot_flow.html) Once SBL is loaded, the second boot stage starts. In this stage, SBL takes charge of the boot and performs the following jobs: 1. Initialize flash driver 2. Read partition table from flash to choose APP image 3. Authenticate selected APP image 4. Load RAM segments to RAM 5. Load RRAM segments to RRAM 6. Verify the hash for each segment 7. Jump to APP entry Note: In the above seven steps, - Step 3 is skipped if the boot is a warm boot. - Step 5 is skipped if the image is an OTA new image. Figure : QCC730 boot sequence: SBL to APP SBL entry SBL entry Flash init Flash init Read partition table for APP image Read partition table for APP image Authenticate APP image Authenticate APP image Load to RAM for RAM segments Load to RAM for RAM segments Load to RRAM for RRAM segments Load to RRAM for RRAM segments Hash verification for each segment Hash verification for each segment Jump to APP entry Jump to APP entry Last Published: Jun 03, 2026 [Previous Topic Configuration BIN binaries](https://docs.qualcomm.com/bundle/publicresource/80-Y8730-2/topics/configuration_bin_images.md) [Next Topic ELF load details during QCC730 boot](https://docs.qualcomm.com/bundle/publicresource/80-Y8730-2/topics/qcc730_boot_elf_load.md)