Armv8.x-A and the SBSA

The Server Base System Architecture (SBSA), provides hardware requirements for servers. The SBSA ensures that operating systems, hypervisors and firmware operate correctly. For servers, where a degree of standardization is important, the SBSA includes rules on which extensions to the architecture must be implemented.

The following table summarizes the SBSA requirements that relate to the Armv8.x-A extensions:

Version Feature SBSA
Level 3 Level 4 Level 5
Armv8.0-A Advanced SIMD Mandatory
Crypto instructions Mandatory (subject to export restrictions)
CRC Mandatory
4KB and 64KB granule Mandatory
16-bit ASID Mandatory
EL2 and EL3 Mandatory
AArch64 at all Exception levels Mandatory
At least six PMU counters Mandatory
At least six breakpoints and four synchronous watchpoints Mandatory
Armv8.1-A 16-bit VMIDs - Mandatory
Virtualization Host Extension - Mandatory
Armv8.2-A RAS - Mandatory (at least minimal implementation)
Persistent memory - Optional (with restrictions)
Armv8.3-A Nested virtualization - - Optional (with restrictions)
Pointer authentication Optional (with restrictions) Mandatory
Armv8.4-A Stage 2 type overrides - - Mandatory
Enhanced nested virtualization - - Mandatory
Activity monitors - - Mandatory
MPAM - - Optional (with restrictions)
SHA3 and SHA512 - - Mandatory (subject to export restrictions)
Generic counter scaling - - Mandatory


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