x86: Support booting SeaBIOS

SeaBIOS is an open source implementation of a 16-bit x86 BIOS.
It can run in an emulator or natively on x86 hardware with the
use of coreboot. With SeaBIOS's help, we can boot some OSes
that require 16-bit BIOS services like Windows/DOS.

As U-Boot, we have to manually create a table where SeaBIOS gets
system information (eg: E820) from. The table unfortunately has
to follow the coreboot table format as SeaBIOS currently supports
booting as a coreboot payload.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a0bd344..5fad794 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -449,6 +449,16 @@
 config DM_KEYBOARD
 	default y
 
+config SEABIOS
+	bool "Support booting SeaBIOS"
+	help
+	  SeaBIOS is an open source implementation of a 16-bit X86 BIOS.
+	  It can run in an emulator or natively on X86 hardware with the use
+	  of coreboot/U-Boot. By turning on this option, U-Boot prepares
+	  all the configuration tables that are necessary to boot SeaBIOS.
+
+	  Check http://www.seabios.org/SeaBIOS for details.
+
 source "arch/x86/lib/efi/Kconfig"
 
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