Linux内核编译技巧

drivers/usb/core/Makefile:
usbcore-y := usb.o hub.o hcd.o urb.o message.o driver.o
usbcore-y += config.o file.o buffer.o sysfs.o endpoint.o
usbcore-y += devio.o notify.o generic.o quirks.o devices.o
usbcore-y += port.o

usbcore-$(CONFIG_OF)        += of.o
usbcore-$(CONFIG_USB_PCI)   += hcd-pci.o
usbcore-$(CONFIG_ACPI)      += usb-acpi.o

obj-$(CONFIG_USB) += usbcore.o
obj-$(CONFIG_USB_LEDS_TRIGGER_USBPORT) += ledtrig-usbport.o