grub, syslinux, live: add live-rescue_rw.cfg

features.in/grub/cfg.in/34live-rescue_rw.cfg

+menuentry $"Rescue LiveCD with sessions support" --id 'rescue_session' {
+  savedefault
+  echo $"Loading Linux vmlinuz$KFLAVOUR ..."
+  linux /boot/vmlinuz$KFLAVOUR fastboot live @initrd_bootargs@ @stagename@=live systemd.unit=live-rescue.target ramdisk_size=@live_size@ nosplash vga=@bootvga@ @rescue_bootargs@ lang=$lang lowmem
+  echo $"Loading initial ramdisk ..."
+  initrd /boot/@initrd@$KFLAVOUR.@initrd_ext@
+}
+

features.in/live/config.mk

@@ -111,6 +111,9 @@ use/live/rescue/extra: use/live/rescue
 	$(call tags,(base || extra || server || misc || fs) \
 		&& !x11 && (rescue || comm || network || security || archive)))
 
+use/live/rescue/rw: use/live/rescue \
+	use/syslinux/live-rescue_rw.cfg use/grub/live-rescue_rw.cfg; @:
+
 # for kiosks
 use/live/runapp: use/live
 	@$(call add,LIVE_PACKAGES,livecd-runapp)

features.in/syslinux/cfg.in/34live-rescue_rw.cfg

+label rescue_session
+  menu label ^Rescue LiveCD with sessions support
+  kernel /boot/vmlinuz
+  append initrd=/boot/@initrd@ fastboot live @initrd_bootargs@ @stagename@=live systemd.unit=live-rescue.target ramdisk_size=@live_size@ live_rw nosplash showopts vga=@bootvga@ @rescue_bootargs@ lowmem
+