Add preliminary support for live kernel upgrade

Signed-off-by: Fil <fil.bergamo@riseup.net>

scripts/InstallScripts/FlashKernelPart.sh

@@ -0,0 +1,148 @@
+#!/bin/sh -e
+
+# This file is part of PrawnOS (http://www.prawnos.com)
+# Copyright (c) 2018 Hal Emmerich <hal@halemmerich.com>
+# Copyright (c) 2020 Fil Bergamo <fil@filberg.eu>
+
+# PrawnOS is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2
+# as published by the Free Software Foundation.
+
+# PrawnOS is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with PrawnOS.  If not, see <https://www.gnu.org/licenses/>.
+
+# -----------------------------------------------
+#              STATIC CONFIGURATION
+# -----------------------------------------------
+#
+# eMMC device name
+emmc_devname=mmcblk2
+#
+# Blank kernel image
+blnk=./blank_kernel
+#
+# Actual kernel image (.kpart)
+kimg=./vmlinux.kpart
+#
+# GPT partition type UUID for "ChromeOS kernel"
+ptype_kernel="FE3A2A5D-4F32-41A7-B725-ACCC3285A309"
+#
+# Kernel partition number
+pnum_kernel=1
+# -----------------------------------------------
+
+# function die():
+# print an error message and exit with the provided code
+# $1 = error message
+# $2 = exit code
+die()
+{
+    redtxt='\033[0;31m'
+    printf "$redtxt$1\n"
+    exit $2
+}
+
+# function get_partition_type_uuid()
+# print the UUID of the gpt partition type
+# for the given partition number on the given device
+# $1 = device (e.g. /dev/mmcblk2)
+# $2 = partition number
+get_partition_type_uuid()
+{
+    cgpt show -i "$2" -t -n -q "$1" 2>/dev/null
+}
+
+# function get_root_partition()
+# print the actual physical device
+# currently mounted as "/"
+get_root_partition()
+{
+    rootfs=$(findmnt / -n -o SOURCE)
+
+    if echo "$rootfs" | grep -q "/dev/mapper" ;then
+	# root filesystem is on luks volume
+	# let's find the physical device behind it
+	rootfs=$(cryptsetup status "$rootfs" | grep "device: " | cut -d ' ' -f 5)
+    fi
+    echo "$rootfs"
+}
+
+
+# ------------- BEGIN SCRIPT EXECUTION --------------------
+
+# Check root or sudo
+[ ! $(id -u) = 0 ] &&
+    die "Please run this script with sudo, or as root" 1
+
+rootfs=$(get_root_partition)
+devname=$(lsblk -no pkname $rootfs | head -n 1)
+devtype=
+kpart=
+
+case "$devname" in
+    $emmc_devname)
+	devtype="Internal eMMC"
+	kpart=/dev/${devname}p$pnum_kernel
+	;;
+    sd*)
+	devtype="USB Stick"
+	kpart=/dev/${devname}$pnum_kernel
+	;;
+    mmcblk[0-9])
+	devtype="External SD card"
+	kpart=/dev/${devname}p$pnum_kernel
+	;;
+    *)
+	die "FAILED to recognize booted device type $devname" 127
+esac
+
+# Check that the selected partition is effectively of type "kernel"
+ptype=$(get_partition_type_uuid /dev/$devname $pnum_kernel)
+[ ! "$ptype" = "$ptype_kernel" ] &&
+    die "FATAL ERROR: unexpected partitioning scheme found. Partition # $pnum_kernel is NOT the kernel partition!" 255
+
+# Check that the needed kernel images exist
+[ ! -e "$kimg" ] &&
+    die "ERROR: cannot find kernel image at $kimg !" 127
+
+[ ! -e "$blnk" ] &&
+    die "ERROR: cannot find blank image at $blnk !" 127
+
+
+# Prompt for user's confirmation
+echo "
+----------------------------
+ /!\\ !!! CAUTION !!! /!\\
+----------------------------
+This will flash a new kernel image onto the running device's kernel partition: $kpart
+The detected running device is: $devtype.
+DO NOT shutdown or reboot before completing the process!
+"
+printf "%s" "Are you REALLY sure you want to continue??? [y/N] "
+
+read ans
+
+[ "$ans" != "y" ] &&
+       [ "$ans" != "Y" ] &&
+       die "Aborted by user. Kernel untouched." 1
+
+# put the kernel in the kernel partition
+dd if="$blnk" of="$kpart" conv=notrunc ||
+    die "FAILED to flash blank kernel on $kpart!" 255
+
+dd if="$kimg" of="$kpart" conv=notrunc ||
+    die "FAILED to flash kernel image on $kpart!" 255
+
+echo "
+The new kernel image has been successfully flashed onto $kpart.
+It's now safe to reboot."
+
+# TODO: install modules. -----------------------------------
+# Right now, there's no easy way to do that on the running machine
+# -----------------------------------------------------------------
+# make -C build/linux-$KVER ARCH=arm INSTALL_MOD_PATH=$outmnt modules_install