8.5.10.6.4 UNIONs

The RUN_SIZE and LOAD_SIZE operators provide a mechanism to distinguish between the size of a UNION's load space and the size of the space where its constituents are going to be copied before they are run. Here is an example:

UNION: run = RAM, LOAD_START(union_load_addr), LOAD_SIZE(union_ld_sz), RUN_SIZE(union_run_sz) { .text1: load = ROM, SIZE(text1_size) { f1.obj(.text) } .text2: load = ROM, SIZE(text2_size) { f2.obj(.text) } }

Here union_ld_sz is going to be equal to the sum of the sizes of all output sections placed in the union. The union_run_sz value is equivalent to the largest output section in the union. Both of these symbols incorporate any padding due to blocking or alignment requirements.