Partition Layout & What Each Partition Does
Posted: Tue Feb 17, 2026 7:19 pm
Partition Layout & What Each Partition Does
Understanding the partition layout is essential before flashing. Here is what each important partition does on MSM8916 devices.
Critical Partitions (DO NOT ERASE)
modemst1 / modemst2
Contains your IMEI and modem calibration data. If you erase these, your modem will not work and your IMEI will be lost. Always back these up!
fsc / fsg
Modem firmware security data. Required for modem operation.
Flashable Partitions
aboot — Application bootloader. This is where you flash lk2nd. It is the first code that runs after the SoC firmware.
boot — Contains the Linux kernel and initramfs (initial RAM filesystem). Device-specific — make sure to use the right image for your board.
rootfs / system — The main Linux root filesystem. This is where Debian and all your software lives. Largest partition on the eMMC.
recoveryfs — Recovery filesystem (if present). Can be used as fallback.
Other Partitions
sbl1 — Secondary bootloader stage 1. Part of Qualcomm boot chain.
rpm — Resource and Power Manager firmware.
tz — TrustZone firmware (ARM secure world).
modem — Modem firmware (DSP). Required for LTE operation.
persist — Persistent storage for WiFi/BT calibration.
Safe Modification Summary to see the full partition table of your device.
Understanding the partition layout is essential before flashing. Here is what each important partition does on MSM8916 devices.
Critical Partitions (DO NOT ERASE)
modemst1 / modemst2
Contains your IMEI and modem calibration data. If you erase these, your modem will not work and your IMEI will be lost. Always back these up!
fsc / fsg
Modem firmware security data. Required for modem operation.
Flashable Partitions
aboot — Application bootloader. This is where you flash lk2nd. It is the first code that runs after the SoC firmware.
boot — Contains the Linux kernel and initramfs (initial RAM filesystem). Device-specific — make sure to use the right image for your board.
rootfs / system — The main Linux root filesystem. This is where Debian and all your software lives. Largest partition on the eMMC.
recoveryfs — Recovery filesystem (if present). Can be used as fallback.
Other Partitions
sbl1 — Secondary bootloader stage 1. Part of Qualcomm boot chain.
rpm — Resource and Power Manager firmware.
tz — TrustZone firmware (ARM secure world).
modem — Modem firmware (DSP). Required for LTE operation.
persist — Persistent storage for WiFi/BT calibration.
Safe Modification Summary
- Safe to flash: aboot, boot, rootfs/system
- Never erase: modemst1, modemst2, fsc, fsg
- Caution: sbl1, tz, rpm (only if you know what you are doing)
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