Terminology
QNX SDP8.0SMMUMAN User's GuideAPIConfigurationUtilities
The following terms are used throughout the SMMUMAN documentation.
- DMA
- Direct Memory Access
- Guest
- A guest is an OS running in a QNX hypervisor qvm process; this process presents the virtual machine (VM) in which the guest runs.
- Guest-physical address
- A memory address in guest-physical memory (see
Guest-physical memory
below). - Guest-physical memory
- The memory assembled for a VM by the qvm process that
creates and configures the VM. ARM calls this assembled memory
intermediate physical memory; Intel calls it guest physical
memory. For simplicity, regardless of the platform, we will use the
term Bugnion, Nieh and Tsafrir use in Hardware and Software Support
for Virtualization (Morgan & Claypool, 2017):
guest-physical memory
, and the corresponding term:guest-physical address
. - Host
- Either the development host (the desktop or laptop, which you can connect to your target system to load a new image or debug), or the hypervisor host domain.
- Host-physical address
- A memory address in host-physical memory (see
Host-physical memory
below). - Host-physical memory
- The physical memory; this is the memory seen by the hypervisor host, or any
other entity running in a non-virtualized environment. (see
Guest-physical memory
above). - Hypervisor
- A microkernel that includes virtualization extensions. In a QNX environment,
these extensions are enabled by adding the
module=qvmdirective in a QNX buildfile. - IOMMU
- Input/Output Memory Management Unit. A memory management unit (MMU) that connects a DMA–capable I/O bus to the main memory. Like a traditional MMU, which translates CPU-visible intermediate addresses to physical addresses, an IOMMU maps device-visible intermediate addresses (also called device addresses or I/O addresses in this context) to physical addresses. This mapping ensures that DMA devices cannot interact with memory outside their bounded areas.
- IPMMU
- Intellectual Property MMU. IOMMU on Renesas R-Car platforms.
- QNX hypervisor
- The running instance of either the non-safety QNX Hypervisor product or the safety-certified QNX Hypervisor for Safety product.
- Reserved memory region
- A reserved memory region is a region in memory required by the
specification for a particular device, typically to hold some information
such as tables the device needs in order to operate. Unless you specify
otherwise, the smmuman service looks after these regions
(see smmu_obj_create_flags in the
SMMUMAN Client API Reference
chapter).Note:A reserved memory region is not the same as a memory area you map to a SMMU object. - SMMU
- System Memory Management Unit. An ARM implementation of an IOMMU.
- VT-d
- Intel Virtualization Technology for Directed I/O (VT-d) is an Intel implementation of an IOMMU.
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