4.4.4 Considerations when working with RW data compression

There are some considerations to be aware of when working with RW data compression.

When working with RW data compression:

  • Use the linker option --map to see where compression has been applied to regions in your code.

  • The linker in RealView Compiler Tools (RVCT) v4.0 and later turns off RW compression if there is a reference from a compressed region to a linker-defined symbol that uses a load address.

  • If you are using an Arm® processor with on-chip cache, enable the cache after decompression to avoid code coherency problems.

Compressed data sections are automatically decompressed at run time, providing __main is executed, using code from the Arm libraries. This code must be placed in a root region. This is best done using InRoot$$Sections in a scatter file.

If you are using a scatter file, you can specify that a load or execution region is not to be compressed by adding the NOCOMPRESS attribute.

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