Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public
Document Table of Contents

4.3.3.4. Bypass Mode

The SMMU supports both global and context-specific bypass modes.

In global bypass mode, all incoming requests bypass address translation. Global bypass can be applied to both secure and non-secure requests independently.

Context-specific bypass allows individual translation contexts to bypass address translation. Software controls this by configuring the Stream Table Entry appropriately.

SMMU_CR0.SMMUEN controls the translation through the non-secure interface and behavior of transactions on non-secure streams. When SMMU_S_IDR1.SECURE_IMPL == 1, (two secure states), SMMUEN controls transaction secure streams and the SMMU might be translating secure transactions, even if SMMUEN == 0.

When SMMU_S_CR0.SMMUEN == 0:

  • Incoming transactions with security state matching do not undergo translation and their behavior is controlled by SMMU_S_GPBA register
  • Configuration or translation structures are not accessed:
    • The SMMU does not access the stream table and ignores the contents of SMMU_S_STRRAB* configuration registers.
    • Translation and configuration cache entries are not inserted or modified.
  • As translation does not occur for bypassing transactions, translation-related events are not recorded.