main/postmarketos-initramfs: switch_root with /dev (MR 3230) (MR 4204)

Mount /dev (and /run) in initramfs so util-linux switch_root can move
the mounts over to the new sysroot before changing root.
BusyBox switch_root doesn't even attempt to move anything so use
util-linux's switch_root for this.

Explicitly disable tests too...

main/postmarketos-initramfs/00-initramfs-base.dirs

@@ -4,6 +4,7 @@
 /etc
 /lib
 /proc
+/run
 /sbin
 /sys
 /sysroot

main/postmarketos-initramfs/00-initramfs-extra-base.files

@@ -2,6 +2,7 @@
 /sbin/btrfs
 /sbin/dmsetup
 /sbin/e2fsck
+/sbin/switch_root
 /usr/sbin/parted
 /usr/sbin/resize2fs
 /usr/sbin/resize.f2fs

main/postmarketos-initramfs/APKBUILD

@@ -5,6 +5,7 @@ pkgver=1.4.0
 pkgrel=0
 pkgdesc="Base files for the postmarketOS initramfs / initramfs-extra"
 url="https://postmarketos.org"
+options="!check"  # no tests
 depends="
 	btrfs-progs
 	busybox-extras
@@ -21,6 +22,7 @@ depends="
 	postmarketos-fde-unlocker
 	postmarketos-mkinitfs
 	unudhcpd
+	util-linux-misc
 	xz
 	"
 source="

main/postmarketos-initramfs/init.sh

@@ -53,10 +53,6 @@ setup_bootchart2
 
 # Switch root
 killall telnetd mdev udevd msm-fb-refresher 2>/dev/null
-umount /proc
-umount /sys
-umount /dev/pts
-umount /dev
 
 # shellcheck disable=SC2093
 exec switch_root /sysroot "$init"

main/postmarketos-initramfs/init_functions.sh

@@ -25,6 +25,8 @@ mount_proc_sys_dev() {
 	# mdev
 	mount -t proc -o nodev,noexec,nosuid proc /proc || echo "Couldn't mount /proc"
 	mount -t sysfs -o nodev,noexec,nosuid sysfs /sys || echo "Couldn't mount /sys"
+	mount -t devtmpfs -o mode=0755,nosuid dev /dev || echo "Couldn't mount /dev"
+	mount -t tmpfs -o nosuid,nodev,mode=0755 run /run || echo "Couldn't mount /run"
 
 	mkdir /config
 	mount -t configfs -o nodev,noexec,nosuid configfs /config
@@ -32,9 +34,6 @@ mount_proc_sys_dev() {
 	# /dev/pts (needed for telnet)
 	mkdir -p /dev/pts
 	mount -t devpts devpts /dev/pts
-
-	# /run (needed for cryptsetup)
-	mkdir /run
 }
 
 create_device_nodes() {