Simple Firmware Interface

Simple Firmware Interface, commonly abbreviated SFI, is a firmware-to-operating-system interface developed by Intel for lightweight hardware description and platform initialization. Rather than representing a conventional consumer brand or a standalone commercial product, SFI is a technical specification and implementation associated particularly with Intel's Moorestown handheld platform. Its purpose was to let firmware expose relatively static information about a system through structured tables in memory, allowing an operating system to discover processors, interrupt controllers, memory layout, timers, power-management information, buses, and other platform characteristics. SFI tables use a shared table-header format and are placed in memory so that the operating system can locate the system table by scanning 16-byte boundaries in the physical-address range from 0x000E0000 through 0x000FFFFF. The specification defines several table types, including CPU, APIC, Memory Map, Idle, Frequency, M-Timer, M-RTC, OEMx, Wake Vector, I²C Device, and SPI Device tables. This table-oriented approach was intended to provide the information needed by a compact, power-sensitive platform without requiring the full complexity of a traditional ACPI implementation. SFI was not entirely separate from ACPI. It provided access to a standard ACPI Extended System Description Table, or XSDT, and could therefore expose selected standard ACPI tables, including the PCI Memory Configuration Table (MCFG). The use of the XSDT also helped avoid namespace collisions between SFI-specific descriptions and ACPI data. In practical terms, this allowed an operating system to use SFI for platform-specific information while retaining access to relevant standardized ACPI structures. Linux became the first operating system to implement SFI support. The core SFI patch was described as approximately 1,000 lines of code, and support was merged during development of Linux 2.6.32, specifically in the 2.6.32-rc1 cycle. The work reflected Intel's effort to support its Moorestown platform and its associated handheld-computing designs through a comparatively small firmware interface. SFI's relevance declined as platform firmware and operating-system support evolved. Linux kernel 5.6 designated SFI as obsolete, and support was subsequently removed in Linux kernel 5.12. These changes indicate that SFI no longer forms part of the actively supported Linux firmware interface. Public reference material does not establish a separate corporate organization, consumer distribution model, independent management team, or financial activity for SFI. It is best understood as a historical Intel firmware technology and technical brand rather than as an operating company or chipmaker.

Simple Firmware Interface was developed by Intel as a lightweight way for firmware to communicate static platform information to an operating system. Its principal context was Intel's Moorestown handheld platform, where a compact firmware description mechanism could provide hardware details without requiring an operating system to depend on a complete and highly complex ACPI implementation. The central design of SFI is a collection of structured tables stored in memory. Each table uses a common header format, while individual tables describe particular platform resources or behaviors. The operating system locates the SFI system table by searching 16-byte-aligned addresses in the physical-memory range from 0x000E0000 through 0x000FFFFF. Once located, the system table can identify additional SFI data structures. Defined table categories include CPU topology, APIC information, memory mapping, processor idle states, frequency data, timer information, real-time-clock data, OEM extensions, wake vectors, I²C devices, and SPI devices. SFI also incorporated a bridge to conventional ACPI data. It could provide access to an ACPI XSDT, allowing operating systems to reach standard ACPI tables such as the PCI Memory Configuration Table. The XSDT arrangement helped keep SFI-specific and ACPI namespaces from colliding. SFI was therefore not simply an alternative naming system for every hardware feature; it was a focused platform interface that could coexist with selected ACPI structures. Linux was the first operating system to implement SFI support. The core patch was approximately 1,000 lines, and the code was merged during the Linux 2.6.32 development cycle, with support present by the 2.6.32-rc1 stage. This integration connected the firmware format to the Linux platform-support code needed for Moorestown-era systems. SFI's lifecycle was relatively short. As Linux firmware support matured and the hardware platforms associated with the interface became less central, the interface ceased to be an active direction for kernel development. Linux kernel 5.6 marked SFI obsolete, and Linux kernel 5.12 removed its support. The available reference material does not document a successor product marketed under the SFI name, nor does it identify an independent company, executive structure, sales channel, or financial record. Consequently, SFI should be catalogued as a historical Intel firmware technology rather than as a conventional corporate or consumer brand.

• 2021

  Removed from Linux 5.12

  [1]Simple Firmware Interfaceen.wikipedia.org

  Linux 5.12 removed SFI support from the kernel.

• 2020

  Marked obsolete in Linux 5.6

  [1]Simple Firmware Interfaceen.wikipedia.org

  The Linux 5.6 kernel marked SFI as obsolete.

• 2010

  SFI draft specification 0.8.2

  [2]Simple Firmware Interface official sitesimplefirmware.org

  A draft 0.8.2 version of the Simple Firmware Interface specification was published by Len Brown and Kerry Vander Kamp.

• 2009

  Linux implementation presented

  [1]Simple Firmware Interfaceen.wikipedia.org

  SFI was described in technical Linux and Linux Symposium material as an Intel firmware interface for lightweight platform description, particularly for Moorestown-class systems.

• 2009

  Linux kernel integration

  [1]Simple Firmware Interfaceen.wikipedia.org

  Support for SFI was merged during the development of Linux 2.6.32, with the implementation present by the 2.6.32-rc1 cycle.

A lightweight firmware interface for exposing static platform information to operating systems, designed especially for Intel Moorestown-based handheld systems.

• Firmware interface

  SFI system table

  The system table is the entry point through which an operating system discovers SFI data. Firmware places SFI structures in memory, and the operating system searches the specified aligned physical-address range to find the common table header and references to platform-specific tables.

• Hardware-description tables

  SFI platform tables

  SFI defines tables for processor information, APIC configuration, memory maps, idle states, frequency data, timers, real-time-clock data, OEM extensions, wake vectors, and I²C and SPI devices. Together these tables provide the static platform information needed by an operating system.

• Firmware interoperability

  SFI ACPI XSDT access

  SFI can expose an ACPI Extended System Description Table, enabling access to standard ACPI structures such as the PCI Memory Configuration Table. This interoperability layer allowed SFI-specific data and selected ACPI information to coexist.

• 2021

  Linux removed SFI supportStrategy

  Background

  Following its obsolete designation in Linux 5.6, SFI was no longer treated as an actively supported firmware interface.

  Action taken

  Linux kernel 5.12 removed SFI support.

  Aftermath

  SFI remained relevant primarily as a historical interface for systems and documentation associated with its original Moorestown-era use.

  Source

• 2020

  Linux marked SFI obsoleteStrategy

  Background

  SFI had become a legacy firmware interface with limited ongoing relevance in the Linux platform-support ecosystem.

  Action taken

  Linux kernel 5.6 classified Simple Firmware Interface as obsolete.

  Aftermath

  The obsolescence designation preceded the later removal of SFI support from Linux 5.12.

  Source

1. 1Simple Firmware Interfaceen.wikipedia.org
2. 2Simple Firmware Interface official sitesimplefirmware.org