[[ext:svadu]]
=== ext:svadu[] Extension for Hardware Updating of A/D Bits

The Svadu extension adds support and CSR controls for hardware updating of PTE A/D bits.

[#norm:Svadu_hw_update_a_d_bits]#If the Svadu extension is implemented, the `menvcfg`.ADUE field is writable.#
[#norm:Svadu_hypervisor_adue_writable]#If the hypervisor extension is additionally implemented, the `henvcfg`.ADUE
field is also writable.#
See <<sec:menvcfg>> and <<sec:henvcfg>> for the definitions of those fields.

<<translation>> defines the semantics of hardware updating of A/D bits.
[#norm:Svadu_disabled_hw_update_falls_back_to_svade]#When hardware updating of A/D bits is disabled, the Svade extension,
which mandates exceptions when A/D bits need be set, instead takes effect.#
The Svade extension is also defined in <<translation>>.