SeaBIOS: have coreboot pass the choice to run optionroms in parallel

Introduce the tunable CONFIG_SEABIOS_THREAD_OPTIONROMS.

Change-Id: Ifd4d9fca7316eb739ff184e54bdc1cdb0262f0c6
Signed-off-by: Idwer Vollering <vidwer@gmail.com>
Reviewed-on: http://review.coreboot.org/5443
Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

src/Kconfig

@@ -624,6 +624,17 @@ config SEABIOS_PS2_TIMEOUT
 	  after powering on. This specifies how long SeaBIOS will wait for the
 	  keyboard controller to become ready before giving up.
 
+config SEABIOS_THREAD_OPTIONROMS
+	prompt "Hardware init during option ROM execution" if PAYLOAD_SEABIOS
+	default n
+	bool
+	help
+	  Allow hardware init to run in parallel with optionrom execution.
+
+	  This can reduce boot time, but can cause some timing
+	  variations during option ROM code execution. It is not
+	  known if all option ROMs will behave properly with this option.
+
 choice
 	prompt "GRUB2 version"
 	default GRUB2_MASTER

src/arch/x86/Makefile.inc

@@ -468,6 +468,7 @@ seabios:
 			AS="$(AS)" CPP="$(CPP)" \
 			CONFIG_SEABIOS_MASTER=$(CONFIG_SEABIOS_MASTER) \
 			CONFIG_SEABIOS_STABLE=$(CONFIG_SEABIOS_STABLE) \
+			CONFIG_SEABIOS_THREAD_OPTIONROMS=$(CONFIG_SEABIOS_THREAD_OPTIONROMS) \
 			OUT=$(abspath $(obj)) IASL="$(IASL)"
 
 filo: