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 6 PMUY counters Mandatory
At least 6 breakpoints and four synchronous watchpoints Mandatory
Armv8.1-A 16-bit VMIDs -


Virtualization Host Extension


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)


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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