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RealView Linker and Utilities Guide

Type 2, one load region and non contiguous execution regions

3.4.2. Type 2, one load region and non contiguous execution regions

An image of this type consists of a single load region, and three execution regions in execution view. The RW execution region is not contiguous with the RO execution region. This approach is used, for example, for ROM-based embedded systems (see Figure 3.4), where RW data is copied from ROM to RAM at startup.

Figure 3.4. Simple type 2 image

Use the following command for images of this type:

armlink ‑‑ro‑base 0x0 ‑‑rw‑base 0xA000

Load view

In the load view, the single load region consists of the RO and RW output sections placed consecutively, for example, in ROM. Here, the RO region is a root region, and the RW region is non root. The ZI output section does not exist at load time. It is created at run‑time.

Execution view

In the execution view, the first execution region contains the RO output section and the second execution region contains the RW and ZI output sections.

The execution address of the region containing the RO output section is the same as its load address, so the RO output section does not have to be moved. That is, it is a root region.

The execution address of the region containing the RW output section is different from its load address, so the RW output section is moved from its load address (from the single load region) to its execution address (into the second execution region). The ZI execution region, and its output section, is placed contiguously with the RW execution region.

Use armlink options ‑‑ro‑base address to specify the load and execution address for the RO output section, and ‑‑rw‑base exec_address to specify the execution address of the RW output section. If you do not use the ‑‑ro‑base option to specify the address, the default value of 0x8000 is used by armlink. For an embedded system, 0x0 is typical for the ‑‑ro‑base value. If you do not use the ‑‑rw‑base option to specify the address, the default is to place RW directly above RO (as in Type 1, one load region and contiguous execution regions).

Note

The execution region for the RW and ZI output sections cannot overlap any of the load regions.

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