Module iommu 

IOMMU (I/O Memory Management Unit) Foundation

Provides DMA address translation and device isolation via Intel VT-d (or equivalent on other architectures). This module handles:

• DMAR table detection from ACPI
• IOMMU unit discovery and capability reading
• Identity mapping for known-safe devices
• DMA coherency flags and scatter-gather list support

Full IOMMU page table management is deferred to a later phase; this module provides the foundation for safe DMA with identity mapping.

Structs

DeviceScope

Device scope entry within DRHD or RMRR structures.

DmaMappedBuffer

A DMA-mapped buffer with coherency and direction tracking.

DmarInfo

Parsed DMAR (DMA Remapping) table information.

DrhdUnit

A DMA Remapping Hardware Unit discovered from the ACPI DMAR table.

IommuContextTable

IOMMU context table (256 entries per PCI bus, page-aligned).

IommuUnit

Represents a parsed IOMMU hardware unit with its capabilities.

RmrrRegion

A Reserved Memory Region Reporting entry.

ScatterGatherEntry

A single entry in a scatter-gather list.

ScatterGatherList

Scatter-gather list for multi-buffer DMA transfers.

Enums

DmaCoherency

DMA coherency policy for buffer allocation.

DmaDirection

DMA direction hint for buffer mapping.

DmarStructureType

DMAR Remapping Structure types (per Intel VT-d specification).

Functions

alloc_dma_buffer

Allocate a physically contiguous DMA buffer.

create_identity_domain

Create an identity domain for DMA address translation.

free_dma_buffer

Free a DMA-mapped buffer.

identity_map_dma

Create an identity mapping for a DMA region.

init

Initialize the IOMMU subsystem by parsing the ACPI DMAR table.

init_iommu_unit

Initialize an IOMMU hardware unit from a parsed DRHD entry.

is_initialized

Check whether IOMMU support has been initialized.

parse_dmar

Parse the ACPI DMAR table from raw bytes.

unmap_dma

Remove a DMA identity mapping.

with_dmar_info

Access parsed DMAR information.