Report the kernel console on the boot screen

Report what console the boot loader is telling the kernel to use:
	o Dual (Serial Primary)
	o Dual (Video Primary)
	o Serial
	o Video

This allows the user to interrupt the boot and tweak the cosnole, if
needed, in a trivial way. Useful for installs where the default
selected may not be quite what you want, or when you are running a
dual setup and need to toggle over to the other console being primary.
The 'c'/'C' keys will do the cycling through the consoles.  Note:
you'll still have to drop into the loader to set details about serial
consoles. And this doesn't change the console the loader is using.

Reviewed by: kevans@
MFC After: 3 days
Differential Revision: https://reviews.freebsd.org/D26573

stand/lua/core.lua

@@ -451,6 +451,40 @@ function core.popFrontTable(tbl)
 	return first_value, new_tbl
 end
 
+function core.getConsoleName()
+	if loader.getenv("boot_multicons") ~= nil then
+		if loader.getenv("boot_serial") ~= nil then
+			return "Dual (Serial primary)"
+		else
+			return "Dual (Video primary)"
+		end
+	else
+		if loader.getenv("boot_serial") ~= nil then
+			return "Serial"
+		else
+			return "Video"
+		end
+	end
+end
+
+function core.nextConsoleChoice()
+	if loader.getenv("boot_multicons") ~= nil then
+		if loader.getenv("boot_serial") ~= nil then
+			loader.unsetenv("boot_serial")
+		else
+			loader.unsetenv("boot_multicons")
+			loader.setenv("boot_serial", "YES")
+		end
+	else
+		if loader.getenv("boot_serial") ~= nil then
+			loader.unsetenv("boot_serial")
+		else
+			loader.setenv("boot_multicons", "YES")
+			loader.setenv("boot_serial", "YES")
+		end
+	end
+end
+
 recordDefaults()
 hook.register("config.reloaded", core.clearCachedKernels)
 return core