WO R K I N G W I T H T H E C P U

MemoryManagement Unit (MMU)

Access permissions and domains

Translated entries

Invalidate entire TLB using R8: TLB Operations register (see “R8:TLB Operations register” on page 97).

Invalidate TLB entry selected by MVA, using R8: TLB Operations register (see “R8:TLB Operations register” on page 97).

Lockdown of TLB entries using R10: TLB Lockdown register (see “R10:TLB Lockdown register” on page 101).

For large and small pages, access permissions are defined for each subpage (1 KB for small pages, 16 KB for large pages). Sections and tiny pages have a single set of access permissions.

All regions of memory have an associated domain. A domain is the primary access control mechanism for a region of memory. It defines the conditions necessary for an access to proceed. The domain determines whether:

Access permissions are used to qualify the access. The access is unconditionally allowed to proceed. The access is unconditionally aborted.

In the latter two cases, the access permission attributes are ignored.

There are 16 domains, which are configured using R3: Domain Access Control register (see “R3:Domain Access Control register” on page 91).

The TLB caches translated entries. During CPU memory accesses, the TLB provides the protection information to the access control logic.

When the TLB contains a translated entry for the modified virtual address (MVA), the access control logic determines whether:

Access is permitted and an off-chip access is required — the MMU outputs the appropriate physical address corresponding to the MVA.

Access is permitted and an off-chip access is not required — the cache services the access.

Access is not permitted — the MMU signals the CPU core to abort.

If the TLB misses (it does not contain an entry for the MVA), the translation table walk hardware is invoked to retrieve the translation information from a translation table in physical memory. When retrieved, the translation information is written into the TLB, possible overwriting an existing value.

At reset, the MMU is turned off, no address mapping occurs, and all regions are marked as noncachable and nonbufferable.

106Hardware Reference NS9215

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Digi NS9215 manual Access permissions and domains Translated entries

NS9215 specifications

The Digi NS9215 is a powerful solution designed for industrial applications that require reliable connectivity and robust performance. Built on a foundation of advanced technologies, the NS9215 serves as a versatile networking device that meets the demands of automation, remote monitoring, and data acquisition.

One of the standout features of the Digi NS9215 is its multi-protocol support. It is capable of handling various communication protocols, including Ethernet, Serial, and Wireless, making it ideal for integration into heterogeneous environments. This flexibility enables users to connect legacy devices to modern networks seamlessly, facilitating smoother data communication across different platforms.

The NS9215 is equipped with powerful processing capabilities, featuring an integrated processor that ensures efficient data handling. This enables the device to perform complex data tasks without compromising performance. Its high-speed connectivity options also allow for rapid data transmission, which is crucial for real-time applications in industrial settings.

Another critical characteristic of the Digi NS9215 is its reliability in harsh environments. Built to withstand extreme temperatures, humidity, and electrical interference, this device assures consistent operation even in challenging conditions. Its rugged design minimizes the risk of failure, making it suitable for deployment in various industrial environments.

Security is a top priority for the Digi NS9215. It comes with advanced security features that protect sensitive data during transmission and prevent unauthorized access. Employing encryption protocols and secure authentication methods, the NS9215 ensures that data integrity and confidentiality are maintained throughout its operation.

The user-friendly interface of the NS9215 allows for easy configuration and management. This ease of use reduces the time required for installation and setup, enabling quick deployment in field operations. Additionally, remote management capabilities enhance operational efficiency, allowing users to monitor device performance and make adjustments from anywhere.

Furthermore, the NS9215 supports extensive scalability options. As organizations grow and evolve, the ability to scale up or adapt the networking capabilities becomes essential. With its modular design, the NS9215 can easily accommodate additional devices and protocols, ensuring longevity and continued relevance in a rapidly changing technological landscape.

In conclusion, the Digi NS9215 is a robust networking device designed for a wide range of industrial applications. Its multi-protocol support, reliability, security features, user-friendly interface, and scalability make it a valuable addition to any industrial network infrastructure, delivering performance and efficiency that businesses can depend on for critical operations.