Add grub configuration to make booting different payloads easier

grub.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+set -e
+
+./util/scripts/config --disable PAYLOAD_SEABIOS
+./util/scripts/config --enable PAYLOAD_GRUB2
+make olddefconfig
+
+make -j $(nproc)
+
+./build/cbfstool build/coreboot.rom add -t raw -f grub/vga -n vgaroms/sgabios.bin
+./build/cbfstool build/coreboot.rom add -t raw -f grub/grub.cfg -n etc/grub.cfg
+./build/cbfstool build/coreboot.rom add-payload -f grub/seabios -n img/seabios
+./build/cbfstool build/coreboot.rom add-payload -f grub/tianocore -n img/tianocore
+
+./build/cbfstool build/coreboot.rom print

grub/grub.cfg

@@ -0,0 +1,6 @@
+insmod regexp
+for img in (cbfsdisk)/img/* ; do
+    menuentry "$img" {
+		chainloader "$1"
+	}
+done