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A shared object file's loadable content is divided into a small number of "segments". Each segment has a set of permission flags: (R)eadable, (W)riteable ans e(X)ecutable. In shared objects built for DAT systems there's normally one RX segment containing instructions and read-only data and one RW section containing non-constant data. The dynamic linker uses the CPU's memory management unit (MMU) to set the access type of the memory allocated to each segment to match the segment's permission flags.
Linker actions step-by-step example
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