ARM Compiler toolchain Using the Linker - ARM Information Center

Image structure and generation
4.7 Type 2 image, one load region and non-contiguous execution regions
4.7.1 Load view
RAM
ROM
4.7.2 Execution view
A Type 2 image 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, where RW data is copied from ROM to
RAM at startup:
RW output section
RO output section
Load view
0xA000
Copy/
decompress
Single
load
region
0x0000
Use the following command for images of this type:
armlink --ro_base 0x0 --rw_base 0xA000
ZI output section
RW output section
RO output section
Execution view
ZI execution
region
RW execution
region
--rw-base value
RO execution
region
--ro-base value
Figure 4-4 Simple type 2 image
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 runtime.
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.
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