postmarketOS mainline (v7.2-rc3) for Samsung Galaxy Tab S9 Wi-Fi (gts9wifi, SM-X710)
=====================================================================================

Testing build v1. Boot chain: mainline kernel with appended DTB, rootfs on
microSD. Nothing on super/userdata/EFS is touched; restoring the stock
boot/init_boot/vendor_boot/dtbo images returns the tablet to Android/UT.

Files
-----
pmos-gts9wifi-mainline-v1-twrp.zip   TWRP-flashable boot bundle
                                     (boot, init_boot, vendor_boot, dtbo, vbmeta)
pmos-gts9wifi-rootfs-v1.img.zst      microSD image (zstd), GNOME, user phablet,
                                     password phablet, sshd enabled

Flashing
--------
1. Write the rootfs to a microSD (>= 8 GB) from a PC:
     zstd -d --stdout pmos-gts9wifi-rootfs-v1.img.zst | sudo dd of=/dev/sdX bs=4M conv=fsync status=progress
   The root partition grows to fill the card on first boot.
2. Insert the card, boot to TWRP, mount /data, push the zip:
     adb push pmos-gts9wifi-mainline-v1-twrp.zip /data/
   and install it from /data via the TWRP menu.
3. Reboot to the OS:
     adb shell twrp reboot system

Status
------
Works: display (2560x1600@120 DSC), touch, GPU (a740/turnip), Wi-Fi (ath11k),
Bluetooth, USB net+host, microSD root, battery telemetry, suspend/resume.
audio DSP and SSC motion sensor firmware included (untested on hardware).
Not yet: S Pen, cameras, fingerprint.