ARM Compiler toolchain Using the Linker - ARM Information Center

7.12 Image symbols
7.12.1 See also
Accessing and managing symbols with armlink
Image symbols are generated by the linker when you use a command-line option to create a
simple image.
The following table shows the image symbols:
Symbol Section type Description
If you are using a scatter file, the image symbols are undefined. If your code accesses any of
these symbols, you must treat them as a weak reference.
The standard implementation of __user_setup_stackheap() uses the value in Image$$ZI$$Limit.
Therefore, if you are using a scatter file you must manually place the stack and heap. You can
do this either:
• in a scatter file using one of the following methods:
— define separate stack and heap regions called ARM_LIB_STACK and ARM_LIB_HEAP
— define a combined region containing both stack and heap called ARM_LIB_STACKHEAP.
• by re-implementing __user_setup_stackheap() to set the heap and stack boundaries.
Tasks
• Linker-defined symbols that are not defined when scatter-loading on page 8-11
• Specifying stack and heap using the scatter file on page 8-12.
Concepts
• Types of simple image on page 4-10
• About weak references and definitions on page 4-32.
Migration and Compatibility:
• C and C++ library changes between RVCT v2.2 and RVCT v3.0 on page 9-5.
Reference
Using ARM ® C and C++ Libraries and Floating-Point Support:
• __user_setup_stackheap() on page 2-60.
Table 7-4 Image symbols
Image$$RO$$Base Output Address of the start of the RO output section.
Image$$RO$$Limit Output Address of the first byte beyond the end of the
RO output section.
Image$$RW$$Base Output Address of the start of the RW output section.
Image$$RW$$Limit Output Address of the byte beyond the end of the ZI
output section. (The choice of the end of the ZI
region rather than the end of the RW region is to
maintain compatibility with legacy code.)
Image$$ZI$$Base Output Address of the start of the ZI output section.
Image$$ZI$$Limit Output Address of the byte beyond the end of the ZI
output section.
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