Android bootloader (Qualcomm LinuxLoader); draws the fastboot screen and verifies boot/init_boot (rooting)
AVB
Android Verified Boot; green = locked and verified, red = rejected
boot / init_boot
kernel / first-stage ramdisk (where the KernelSU loader lives)
boot_a / boot_b
the two copies of the boot partition. The tablet always boots boot_a; Linux runs by writing its boot image there. boot_b is never booted and keeps a copy of your stock Android boot image (android/README.md)
the way back
that copy in boot_b, with its SHA-256 recorded at install time: copying it into boot_a starts Android again. Every tool checks the hash before writing (install-manual.md, step 2, switching)
virtual A/B
small partitions exist twice, super only once; slot _b cannot boot here
LUN
a UFS logical unit; most boot partitions are on LUN 4, userdata on LUN 0
GBL / efisp
an EFI application ABL loads from the efisp partition; the patched one makes ABL treat itself as unlocked (rooting)
baldur-root, baldur-root-sd, tb323fu-*
GPT partition names the initramfs looks for: baldur-root usually on the internal storage (UFS), baldur-root-sd on the microSD card, tb323fu-* (e.g. tb323fu-ubuntu) for more systems on the card. Roots are always found by name, never by number (initramfs)
state root
the first present of baldur-root, baldur-root-sd, then the tb323fu-* partitions in sorted order. It holds the boot selection (/etc/tb323fu/boot-next, boot-default) and the kernel-update state (/var/lib/tb323fu/) for all systems (helper.md → Multiboot)
root selection
the built-in initramfs picks the root to boot: the one-shot next choice, the default, the state root, then every other candidate; optionally a boot menu (volume up) (initramfs)
shared modules
the kernel's modules travel inside its boot image as one squashfs, which the initramfs mounts on the chosen root's /lib/modules/<release>; so a kernel update needs nothing installed in the roots. A root can opt out (own mode) (initramfs)
a newly installed kernel starts on trial: the initramfs counts its starts, and the third start of a kernel that was never kept writes the good kernel back (helper.md → Kernel updates)
Keep
confirms a kernel on trial by hand (Open Device Helper or tb323fu-ctl kernel keep). Stable-channel kernels are kept automatically after 90 s; testing-channel kernels and kernels from a file wait for Keep
good kernel
the last confirmed kernel, saved as linux-good.img on the state root; what a failed trial, Go Back and Android's Switch to Linux fall back to
release (kernel-tNN, helper-vX.Y.Z)
the kernels and helper versions published on the project's GitHub Releases; a kernel release is an Image, never a boot image (install-manual.md)
Qualcomm emergency download mode (USB 05c6:9008); Sahara uploads the loader, Firehose reads and writes partitions. The real recovery mode (recovery)
900E
crash dump mode (USB 05c6:900E); one-shot dump session, not a way to write; the tablet resets afterwards
LTBox
the PC tool that backs up the tablet over EDL and roots Android without unlocking the bootloader (patched GBL plus KernelSU) (rooting)
KernelSU
the root manager on Android, in init_boot (LKM mode) (rooting)
Switch to Linux
the KernelSU module whose Action button writes the Linux boot image to boot_a, verifies it and restarts (android/README.md)
back-to-android
the Linux tool that copies boot_b into boot_a and restarts into Android; the emergency key (volume up + volume down for 10 s) runs it too (after-install.md)
the system service (tb323fu-helperd), CLI (tb323fu-ctl), settings app and GNOME quick-settings tile for the tablet's own settings: charging, refresh rate, performance, lights, multiboot, kernel and helper updates (helper.md)
guided installer
tools/install/install.sh: one script on the PC that does the whole install against a rooted tablet (install.md, tools/install)
distribution module
the small shell file that builds one system's root filesystem for the guided installer (DISTRO=ubuntu, arch, nixos, …); your own can be passed by path (distribution modules)
platform files
the distribution-neutral files every root needs: udev rules, systemd units, audio and sensor configuration, the emergency key (userspace/platform)
firmware extraction
the firmware is not shipped; it is copied from your own tablet's Android /vendor with a script and checked against a manifest (firmware, install-manual.md, step 1)
audio topology
LENOVO-TB323FU-tplg.bin, which tells the audio DSP driver which audio paths exist; without it the sound card does not appear. Unlike the rest of the firmware it is built in this repository from open sources (firmware/audio)