SeaBIOS is an

open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

implementation of an

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...

BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the ...

, serving as a freely available

firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...

for x86 systems. Aiming for compatibility, it supports standard BIOS features and calling

interfaces Interface or interfacing may refer to: Academic journals * Interface (journal), ''Interface'' (journal), by the Electrochemical Society * ''Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Lin ...

that are implemented by a typical proprietary x86 BIOS. SeaBIOS can either run on bare hardware as a

coreboot coreboot, formerly known as LinuxBIOS, is a software project aimed at replacing proprietary firmware (BIOS or UEFI) found in most computers with a lightweight firmware designed to perform only the minimum number of tasks necessary to load and r ...

payload, or can be used directly in

emulator In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run so ...

s such as

QEMU QEMU is a free and open-source emulator (Quick EMUlator). It emulates the machine's processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it to run a variety of guest ...

and

Bochs Bochs (pronounced "box") is a portable IA-32 and x86-64 IBM PC compatible emulator and debugger mostly written in C++ and distributed as free software under the GNU Lesser General Public License. It supports emulation of the processor(s) (includin ...

. Initially, SeaBIOS was based on the open-source BIOS implementation included with the Bochs emulator. The project was created with intentions to allow native usage on x86 hardware, and to be based on an improved and more easily extendable internal

source code In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the wo ...

implementation.

Features

Features supported by SeaBIOS include the following: * Graphical

bootsplash A bootsplash, also known as a bootscreen, is a graphical representation of the boot process of the operating system. A bootsplash can be a simple visualization of the scrolling boot messages in the console, but it can also present graphics or so ...

screen (JPEG and BMP) * USB keyboard and mouse support *

USB Mass Storage The USB mass storage device class (also known as USB MSC or UMS) is a set of computing communications protocols, specifically a USB Device Class, defined by the USB Implementers Forum that makes a USB device accessible to a host computing device ...

boot support *

USB Attached SCSI USB Attached SCSI (UAS) or USB Attached SCSI Protocol (UASP) is a computer protocol used to move data to and from USB storage devices such as hard drives (HDDs), solid-state drives (SSDs), and thumb drives. UAS depends on the USB protocol, and u ...

boot support * ATA support *

AHCI The Advanced Host Controller Interface (AHCI) is a technical standard defined by Intel that specifies the register-level interface of Serial ATA (SATA) host controllers in a non-implementation-specific manner in its motherboard chipsets. The ...

support *

NVMe NVM Express (NVMe) or Non-Volatile Memory Host Controller Interface Specification (NVMHCIS) is an open, logical-device interface specification for accessing a computer's non-volatile storage media usually attached via PCI Express (PCIe) bus. The ...

support *

El Torito El Torito (Spanish for "the little bull") is an American chain that serves Mexican food. El Torito operates 69 restaurants primarily in California.BIOS Boot Specification An Option ROM for the PC platform (i.e. the IBM PC and derived successor computer systems) is a piece of firmware that resides in ROM on an expansion card (or stored along with the main system BIOS), which gets executed to initialize the device ...

(BBS) * Rebooting on

Control-Alt-Delete Control-Alt-Delete (often abbreviated to Ctrl+Alt+Del, also known as the "three-finger salute" or "Security Keys") is a computer keyboard command on IBM PC compatible computers, invoked by pressing the Delete key while holding the Control key, C ...

key press *

Network booting Network booting, shortened netboot, is the process of booting a computer from a network rather than a local drive. This method of booting can be used by routers, diskless workstations and centrally managed computers (thin clients) such as publi ...

support e.g.

iPXE iPXE is an open-source implementation of the Preboot eXecution Environment (PXE) client software and bootloader, created in 2010 as a fork of gPXE (gPXE was named Etherboot until 2008).gPXE gPXE is an open-source Preboot eXecution Environment (PXE) client firmware implementation and bootloader derived from Etherboot. It can be used to enable computers without built-in PXE support to boot from the network, or to extend an existing ...

Logical block addressing Logical block addressing (LBA) is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disk drives. LBA is a particularly simple linear addressi ...

(LBA) * POST Memory Manager (PMM) *

Paravirtualization In computing, paravirtualization or para-virtualization is a virtualization technique that presents a software interface to the virtual machines which is similar, yet not identical, to the underlying hardware–software interface. The intent o ...

Xen Xen (pronounced ) is a type-1 hypervisor, providing services that allow multiple computer operating systems to execute on the same computer hardware concurrently. It was originally developed by the University of Cambridge Computer Laboratory an ...

HVM,

VirtIO QEMU is a free and open-source emulator (Quick EMUlator). It emulates the machine's processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it to run a variety of guest ...

* Coreboot Payloads ( LZMA compressed) * PCI Firmware Specification * SeaBIOS as a

Compatibility Support Module UEFI (Unified Extensible Firmware Interface) is a set of specifications written by the UEFI Forum. They define the architecture of the platform firmware used for booting and its interface for interaction with the operating system. Examples of f ...

(CSM) for

Unified Extensible Firmware Interface UEFI (Unified Extensible Firmware Interface) is a set of specifications written by the UEFI Forum. They define the architecture of the platform firmware used for booting and its interface for interaction with the operating system. Examples of ...

(UEFI) and Open Virtual Machine Firmware (OVMF) * Virtual machine host notification of paravirtualized guests which panic via the pvpanic driver * A patch exists to load the

SLIC table In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the b ...

from a licensed OEM Windows BIOS. *

Trusted Platform Module Trusted Platform Module (TPM, also known as ISO/IEC 11889) is an international standard for a secure cryptoprocessor, a dedicated microcontroller designed to secure hardware through integrated cryptographic keys. The term can also refer to a ch ...

Enhanced Disk Drive INT 13h is shorthand for BIOS interrupt call 13 hex, the 20th interrupt vector in an x86-based (IBM PC-descended) computer system. The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and ...

(EDD) (

INT 13H INT 13h is shorthand for BIOS interrupt call 13 hex, the 20th interrupt vector in an x86-based (IBM PC-descended) computer system. The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and ...

extensions) *

e820 e820 is shorthand for the facility by which the BIOS of x86-based computer systems reports the memory map to the operating system or boot loader. It is accessed via the int 15h call, by setting the register to value E820 in hexadecimal. It re ...

memory map *

Protected mode In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as virtual memory, paging and safe multi-tasking d ...

interfaces, e.g. APM, Legacy PnP, DMI, MPS,

SMBIOS In computing, the System Management BIOS (SMBIOS) specification defines data structures (and access methods) that can be used to read management information produced by the BIOS of a computer. This eliminates the need for the operating system to ...

VBE VESA BIOS Extensions (VBE) is a VESA standard, currently at version 3, that defines the interface that can be used by software to access compliant video boards at high resolutions and bit depths. This is opposed to the "traditional" INT 10H, in ...

, and

ACPI Advanced Configuration and Power Interface (ACPI) is an open standard that operating systems can use to discover and configure computer hardware components, to perform power management (e.g. putting unused hardware components to sleep), auto c ...

System Management Mode System Management Mode (SMM, sometimes called ring −2 in reference to protection rings) is an operating mode of x86 central processor units (CPUs) in which all normal execution, including the operating system, is suspended. An alternate ...

It does not support ESCD. SeaBIOS does not support Intel ME or

AMD PSP The AMD Platform Security Processor (PSP), officially known as AMD Secure Technology, is a trusted execution environment subsystem incorporated since about 2013 into AMD microprocessors. According to an AMD developer's guide, the subsystem is "r ...

or its modules. SeaBIOS's boot device selection menu can be accessed by pressing during the boot process.

Uses

SeaBIOS can run natively on x86 hardware, in which case it is loaded by either

Libreboot Libreboot (briefly known as GNU Libreboot) is a free software project based on coreboot, aimed at replacing the proprietary BIOS firmware contained by most computers. Libreboot is a lightweight system designed to perform only the minimum number ...

as a payload; it runs on 386 and later processors, and requires a minimum of 1 MB of

RAM Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...

. Compiled SeaBIOS images can be flashed into supported motherboards using flashrom. SeaBIOS also runs inside an emulator; it is the default BIOS for the

and KVM virtualization environments, and can be used with the

emulator. It is also included in some

Chromebook A Chromebook (sometimes stylized in lowercase as chromebook) is a laptop or tablet running the Linux-based ChromeOS as its operating system. Initially designed to heavily rely on web applications for tasks using the Google Chrome browser, Chromeb ...

s, although it is not used by

ChromeOS ChromeOS, sometimes stylized as chromeOS and formerly styled as Chrome OS, is a Linux-based operating system designed by Google. It is derived from the open-source ChromiumOS and uses the Google Chrome web browser as its principal user interfac ...

Development

Most of the SeaBIOS source code is written in C, with its build system relying on the standard

GNU toolchain The GNU toolchain is a broad collection of programming tools produced by the GNU Project. These tools form a toolchain (a suite of tools used in a serial manner) used for developing software applications and operating systems. The GNU toolchain pl ...

. SeaBIOS has been tested with various bootloaders and operating systems, including

GNU GRUB GNU GRUB (short for GNU GRand Unified Bootloader, commonly referred to as GRUB) is a boot loader package from the GNU Project. GRUB is the reference implementation of the Free Software Foundation's Multiboot Specification, which provides a use ...

, LILO, SYSLINUX,

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...

FreeDOS FreeDOS (formerly Free-DOS and PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running Legacy system, legacy software and supporting embedded system ...

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

NetBSD NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is a ...

and

OpenBSD OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project em ...

References

External links

*
Find your way through the x86 firmware maze
covers the SeaBIOS boot sequence and memory maps {{Firmware and booting 2008 software Free BIOS implementations Free software programmed in C Open-source firmware

Features

Uses

Development

See also

References

External links