 RealView Linker and Utilities Guide | |
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RealView Linker and Utilities Guide
Preface Introduction The Linker Command Syntax Using the Basic Linker Functionality Specifying the image structure
Building blocks for objects and images Load view and execution view of an image Specifying an image memory map Image entry points Section placement Ordering input sections by attribute Using FIRST and LAST to place sections Aligning sections Ordering execution regions containing Thumb code Optimizations and modifications Common debug section elimination Common group or section elimination Unused section elimination Unused function elimination Linker feedback RW data compression PI to absolute veneers Veneer generation Reuse of veneers with overlay execution regions Branch inlining Using command-line options to create simple images Type 1, one load region and contiguous execution r Type 2, one load region and non contiguous executi Type 3, two load regions and non contiguous execut Using command-line options to handle C++ exception Getting information about images Using image-related information Accessing Image Symbols Using Scatter-loading Description Files Using the ARM Librarian Using fromelfType 2, one load region and non contiguous execution regions
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| Home > Using the Basic Linker Functionality > Using command-line options to create simple images > 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.
Use the following command for images of this type:
armlink ‑‑ro‑base 0x0 ‑‑rw‑base 0xA000
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.
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 to specify the load and execution address for the RO output section, and address‑‑rw‑base to specify the execution address of the RW output section. If you do not use the exec_address‑‑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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