README-P2

extroot/README.md

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+# OpenWRT 24.10.0 Extroot on XE-300
+
+## 1. Insert card & install required packages
+
+opkg update
+opkg install block-mount kmod-fs-ext4 kmod-usb-storage e2fsprogs
+
+block-mount - block info, fstab handling, extroot logic
+kmod-fs-ext4 - kernel driver for ext4 filesystem
+kmod-usb-storage -  makes the SD slot show up as /dev/sda
+e2fsprogs - provides mkfs.ext4
+
+## 2. Confirm the SD card is /dev/sda and /dev/sda1
+
+Check dmesg:
+
+dmesg | grep -i sd
+
+
+Sample Output:
+sd 0:0:0:0: [sda] 1000005632 512-byte logical blocks: (512 GB/477 GiB)
+sda: sda1
+sd 0:0:0:0: [sda] Attached SCSI removable disk
+
+
+## 3. Format /dev/sda1 as ext4 for extroot
+mkfs.ext4 -L extroot /dev/sda1
+
+You should see output ending with success and a UUID.
+
+## 4. Grab the UUID and create the extroot fstab entry
+UUID=$(block info | awk -F\" '/sda1/ {print $2}')
+echo $UUID
+
+Sample UUID output:
+
+4851f00e-696b-47d3-a529-82c2aca292db
+
+Now write the minimal extroot config using uci:
+
+uci set fstab.extroot="mount"
+uci set fstab.extroot.uuid="$UUID"
+uci set fstab.extroot.target="/overlay"
+uci set fstab.extroot.fstype="ext4"
+uci set fstab.extroot.enabled="1"
+uci commit fstab
+
+Sanity-check the file:
+
+cat /etc/config/fstab
+
+Sample output:
+
+config global
+    option anon_swap '0'
+    option anon_mount '0'
+    option auto_swap '1'
+    option auto_mount '1'
+    option delay_root '5'
+    option check_fs '0'
+
+config mount 'extroot'
+    option uuid '4851f00e-696b-47d3-a529-82c2aca292db'
+    option target '/overlay'
+    option fstype 'ext4'
+    option enabled '1'
+
+
+## 5. Reboot into extroot
+
+reboot
+
+Wait for the router to come back up, then SSH in again.
+
+## 6. Verify that the SD card is now your root overlay
+
+df -h
+
+Expected output:
+
+Filesystem           Size  Used Available Use% Mounted on
+/dev/root            4.0M  4.0M        0 100% /rom
+tmpfs                58.7M  200.0K    58.5M  0% /tmp
+/dev/sda1           468.3G  2.1M     444.4G  0% /overlay
+overlayfs:/overlay  468.3G  2.1M     444.4G  0% /
+
+
+Explanation:
+
+/dev/root at /rom → read-only squashfs from flash
+/dev/sda1 at /overlay → SD card is the writable layer
+overlayfs:/overlay on / → full rootfs = ROM + SD overlay
+You now have a 468 GB OpenWrt box.
+
+No /rwm mount
+No copy of internal overlay
+This is a clean, SD-only overlay setup.