1mem_ss = ss.source_set() 2mem_ss.add(files('memory-device.c')) 3mem_ss.add(when: 'CONFIG_DIMM', if_true: files('pc-dimm.c')) 4mem_ss.add(when: 'CONFIG_NVDIMM', if_true: files('nvdimm.c')) 5 6softmmu_ss.add_all(when: 'CONFIG_MEM_DEVICE', if_true: mem_ss) 7