The '''Server Base System Architecture''' ('''SBSA''') is a hardware system architecture for servers based on 64-bit ARM processors.<ref>{{cite news |author=Peter Bright |date=30 January 2014 |title=ARM finally defines a platform as it sets its sights on the server room |publisher=Ars Technica |url=https://arstechnica.com/information-technology/2014/01/arm-finally-defines-a-platform-as-it-sets-its-sights-on-the-server-room/ }}</ref><ref>{{cite news |author=Johan De Gelas |date=29 January 2014 |title=ARM and Partners Deliver First ARM Server Platform Standard |publisher=AnandTech |url=http://www.anandtech.com/show/7721/arm-and-partners-deliver-first-arm-server-platform-standard |archive-url=https://web.archive.org/web/20140131074619/http://anandtech.com/show/7721/arm-and-partners-deliver-first-arm-server-platform-standard |url-status=dead |archive-date=January 31, 2014 }}</ref><ref>{{cite press release |title=ARM Ecosystem Collaborates to Deliver Initial Server Platform Standard |date=29 January 2014 |publisher=ARM Holdings |url=http://www.arm.com/about/newsroom/arm-ecosystem-collaborates-to-deliver-initial-server-platform-standard.php }}</ref><ref>{{cite news |author=Jonathan Corbet |date=5 February 2014 |title=ARM, SBSA, UEFI, and ACPI |publisher=LWN.net |url=https://lwn.net/Articles/584123/ }}</ref>
== Rationale ==
Historically, ARM-based products have often been tailored for specific applications and power profiles. Variation between ARM-based hardware platforms has been an impediment requiring operating system adjustments for each product.
The SBSA seeks to strengthen the ARM ecosystem by specifying a minimal set of standardized features so that an OS built for this standard platform should function correctly without modification on all hardware products compliant with the specification.
== Features ==
* CPU features * Memory management * Peripheral access * Interrupts * Watchdog (errant system detection)
Existing specifications for USB, PCIe, ACPI, TPM, and other standards are incorporated to solidify the specification.
=== Server Base Boot Requirements === Firmware issues are addressed separately in the Server Base Boot Requirements (SBBR) specification.<ref>{{Cite web|title=Server and Infrastructure|url=https://developer.arm.com/architectures/platform-design/server-systems|last=Ltd|first=Arm|website=ARM Developer|language=en|access-date=2020-05-13}}</ref>
== Platform validation ==
The Architecture Compliance Suite (ACS) checks whether an environment is compliant with the SBSA specification, and is provided under an Apache 2 open source license. It is available at https://github.com/ARM-software/sbsa-acs.
== Compliance levels ==
The specification defines levels of compliance, with level 0 being the most basic, and successive levels building on prior levels. In the words of the spec, "Unless explicitly stated, all specification items belonging to level N apply to levels greater than N."
=== Level 0, 1, and 2 ===
Levels 0, 1, and 2 have been deprecated and folded into level 3.
=== Level 3 ===
Level 3 contains base-level specifications for:
* PE (Processing Element--a core) features * Memory map * Interrupt controller * PPI (peripheral interrupt) assignments * MMU behavior * Clock and timer subsystem * Wake up semantics * Power state semantics * Watchdogs * Peripheral subsystems
=== Level 4 ===
Extends level 3, e.g. with support for RAS fault recovery extensions of ARMv8.2 spec.
=== Level 5 ===
Extends level 4, e.g. with support for stage 2 translation control from hypervisor as specified in ARMv8.4.
=== Level 6 ===
Extends level 5, e.g. with support for speculative execution safety features.
=== Level 7 ===
Extends level 6, e.g. with support for Arm Memory System Resource Partitioning and Monitoring (MPAM) and Performance Monitoring Unit (PMU) features.
== Versions ==
=== Initial public version ===
Initial public version of the SBSA was announced on January 29, 2014.
=== SBSA Version 3.0 ===
SBSA Version 3.0 was released on February 1, 2016.
=== SBSA Version 5.0 ===
SBSA Version 5.0 was released on May 30, 2018.
=== SBSA Version 6.0 ===
SBSA Version 6.0 was released on September 16, 2019.
=== SBSA Version 6.1 ===
SBSA Version 6.1 was released on September 15, 2020.
=== SBSA Version 7.0 ===
SBSA Version 7.0 was released on January 31, 2021.
=== SBSA Version 7.1 ===
SBSA Version 7.1 was released on October 6, 2022.
== See also ==
== References == {{reflist}}
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Category:ARM architecture Category:Computer hardware standards