bin/kexec-select-boot/reboot/recovery: reuse reboot+DEBUG conditional prompt for recovery shell access, state where debug logs are in centralized way

Note for linuxboot#1888:
warn in code is used mostly to actually warn user of something requiring his attention, and pausing for 2 seconds.

Goal is:
die: blocking: tell user that something failed, requiring acknowledgement for corrective actions.
warn: display "WARNING:" prepended messages which pauses for 2 seconds prior of continuing. This is not an error, nor INFO
INFO: gives a trace to the user when in QUIET mode, under /tmp/debug.log related to core components output, typically related to measurements traces.

Consequently, putting what is currently under warn->INFO wold be console silenced. We want to get rid of manual "echo +++++" messages.
So it seems we lack what is currently named INFO to go into measurement_log, and INFO (green), warn (yellow) and die (red) messages to console.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Author: tlaurion

initrd/bin/kexec-select-boot

@@ -314,17 +314,7 @@ user_select() {
 			# continue below to boot the new default option
 			true
 		else
-			echo "+++ Rebooting to start the new default option"
-			sleep 2
-			if [ "$CONFIG_DEBUG_OUTPUT" != "y" ]; then
-				reboot ||
-					die "!!! Failed to reboot system"
-			else
-				DEBUG "Rebooting is required prior of booting default boot entry"
-				# Instead of rebooting, drop to a recovery shell
-				# for a chance to inspect debug output
-				recovery "Entering recovery to permit inspection of /tmp/debug.log output, reboot to continue"
-			fi
+			warn "Rebooting to start the new default option"
 		fi
 	fi
 

initrd/bin/reboot

@@ -7,7 +7,8 @@ if [ "$CONFIG_DEBUG_OUTPUT" = "y" ]; then
 	#Generalize user prompt to continue reboot or go to recovery shell 
 	read -r -n 1 -s -p "Press Enter to continue reboot or 'r' to go to recovery shell: " REPLY 
 	echo 
-	if [ "$REPLY" = "r" ] || [ "$REPLY" = "R" ]; then 
+	if [ "$REPLY" = "r" ] || [ "$REPLY" = "R" ]; then
+		warn "Use 'less /tmp/debug.log' to see the debug log content"
 		recovery "Reboot call bypassed to go into recovery shell to debug"
 	fi 
 fi