esp-idf/tools/test_apps/build_system/ldgen_test/main/linker.lf

[mapping:main]
archive: libmain.a
entries:
    * (noflash)
    src1 (default)
    src1:func1 (noflash);
        text->iram0_text KEEP() ALIGN(9) ALIGN(12, post) SURROUND(sym1)
    src1:func2 (rtc)