path: root/doc
diff options
authorBin Meng <>2016-02-28 23:54:52 -0800
committerBin Meng <>2016-03-17 10:27:22 +0800
commit2e9ae222f152dde8b2cfe15d5042331e0fa4b8f7 (patch)
tree5cc3ff005e10bcd8c16d16ed311971964b83557f /doc
parent2830bc7d46902e5bdc875feeac52aa615a967989 (diff)
x86: Document how to play with SeaBIOS
Boting SeaBIOS is done via U-Boot's bootelf command. Document this. Signed-off-by: Bin Meng <> Reviewed-by: Simon Glass <>
Diffstat (limited to 'doc')
1 files changed, 55 insertions, 2 deletions
diff --git a/doc/README.x86 b/doc/README.x86
index d3fea5d56f..41acf0bb92 100644
--- a/doc/README.x86
+++ b/doc/README.x86
@@ -669,6 +669,58 @@ environment variables if you add this to minnowmax.h:
#define CONFIG_EXTRA_ENV_SETTINGS "boot=zboot 03000000 0 04000000 ${filesize}"
+Test with SeaBIOS
+SeaBIOS [14] 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 U-Boot. With its
+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 various system
+information (eg: E820) from. The table unfortunately has to follow the coreboot
+table format as SeaBIOS currently supports booting as a coreboot payload.
+To support loading SeaBIOS, U-Boot should be built with CONFIG_SEABIOS on.
+Booting SeaBIOS is done via U-Boot's bootelf command, like below:
+ => tftp bios.bin.elf;bootelf
+ Using e1000#0 device
+ TFTP from server; our IP address is
+ ...
+ Bytes transferred = 122124 (1dd0c hex)
+ ## Starting application at 0x000ff06e ...
+ SeaBIOS (version rel-1.9.0)
+ ...
+bios.bin.elf is the SeaBIOS image built from SeaBIOS source tree.
+Make sure it is built as follows:
+ $ make menuconfig
+Inside the "General Features" menu, select "Build for coreboot" as the
+"Build Target". Inside the "Debugging" menu, turn on "Serial port debugging"
+so that we can see something as soon as SeaBIOS boots. Leave other options
+as in their default state. Then,
+ $ make
+ ...
+ Total size: 121888 Fixed: 66496 Free: 9184 (used 93.0% of 128KiB rom)
+ Creating out/bios.bin.elf
+Currently this is tested on QEMU x86 target with U-Boot chain-loading SeaBIOS
+to install/boot a Windows XP OS (below for example command to install Windows).
+ # Create a 10G disk.img as the virtual hard disk
+ $ qemu-img create -f qcow2 disk.img 10G
+ # Install a Windows XP OS from an ISO image 'winxp.iso'
+ $ qemu-system-i386 -serial stdio -bios u-boot.rom -hda disk.img -cdrom winxp.iso -smp 2 -m 512
+ # Boot a Windows XP OS installed on the virutal hard disk
+ $ qemu-system-i386 -serial stdio -bios u-boot.rom -hda disk.img -smp 2 -m 512
+This is also tested on Intel Crown Bay board with a PCIe graphics card, booting
+SeaBIOS then chain-loading a GRUB on a USB drive, then Linux kernel finally.
Development Flow
@@ -736,7 +788,7 @@ debug serial port may be useful here. See setup_internal_uart() for an example.
During the U-Boot porting, one of the important steps is to write correct PIRQ
routing information in the board device tree. Without it, device drivers in the
Linux kernel won't function correctly due to interrupt is not working. Please
-refer to U-Boot doc [14] for the device tree bindings of Intel interrupt router.
+refer to U-Boot doc [15] for the device tree bindings of Intel interrupt router.
Here we have more details on the intel,pirq-routing property below.
intel,pirq-routing = <
@@ -833,4 +885,5 @@ References
-[14] doc/device-tree-bindings/misc/intel,irq-router.txt
+[15] doc/device-tree-bindings/misc/intel,irq-router.txt
OpenPOWER on IntegriCloud