When you compiled the kernel and modules before did it create a KO file such as serial.ko? If so then you'd have to rebuild the kernel module which depends on this particular source file. For that you can search the Makefiles to see where the source is used. If it was compiled to be internal to the kernel, then you have to rebuild the kernel binary.

A suggestion is to modify the source in the tree where you did your original build and re-do the original build starting with the kernel build. If that source does not get recompiled, then it's part of the modules build. So then rebuild the modules and keep the log of that build, like set your window recall to a very large number or save the log as the build runs, and then check the top level module make which is entered for when that source is compiled. That way you can just build the particular module which it applies for and copy the KO file over to test your changes. But first you need to determine if that was included internally in the kernel, or not.

No, it not created serial.ko but created individual kernel object files like option.ko, sierra.ko and so on.

This is the make file in serial folder

#
# Makefile for the USB serial device drivers.
#

# Object file lists.

obj-$(CONFIG_USB_SERIAL) += usbserial.o

usbserial-y := usb-serial.o generic.o bus.o

usbserial-$(CONFIG_USB_SERIAL_CONSOLE) += console.o

obj-$(CONFIG_USB_SERIAL_AIRCABLE) += aircable.o
obj-$(CONFIG_USB_SERIAL_ARK3116) += ark3116.o
obj-$(CONFIG_USB_SERIAL_BELKIN) += belkin_sa.o
obj-$(CONFIG_USB_SERIAL_CH341) += ch341.o
obj-$(CONFIG_USB_SERIAL_CP210X) += cp210x.o
obj-$(CONFIG_USB_SERIAL_CYBERJACK) += cyberjack.o
obj-$(CONFIG_USB_SERIAL_CYPRESS_M8) += cypress_m8.o
obj-$(CONFIG_USB_SERIAL_DEBUG) += usb_debug.o
obj-$(CONFIG_USB_SERIAL_DIGI_ACCELEPORT) += digi_acceleport.o
obj-$(CONFIG_USB_SERIAL_EDGEPORT) += io_edgeport.o
obj-$(CONFIG_USB_SERIAL_EDGEPORT_TI) += io_ti.o
obj-$(CONFIG_USB_SERIAL_EMPEG) += empeg.o
obj-$(CONFIG_USB_SERIAL_F81232) += f81232.o
obj-$(CONFIG_USB_SERIAL_FTDI_SIO) += ftdi_sio.o
obj-$(CONFIG_USB_SERIAL_GARMIN) += garmin_gps.o
obj-$(CONFIG_USB_SERIAL_IPAQ) += ipaq.o
obj-$(CONFIG_USB_SERIAL_IPW) += ipw.o
obj-$(CONFIG_USB_SERIAL_IR) += ir-usb.o
obj-$(CONFIG_USB_SERIAL_IUU) += iuu_phoenix.o
obj-$(CONFIG_USB_SERIAL_KEYSPAN) += keyspan.o
obj-$(CONFIG_USB_SERIAL_KEYSPAN_PDA) += keyspan_pda.o
obj-$(CONFIG_USB_SERIAL_KLSI) += kl5kusb105.o
obj-$(CONFIG_USB_SERIAL_KOBIL_SCT) += kobil_sct.o
obj-$(CONFIG_USB_SERIAL_MCT_U232) += mct_u232.o
obj-$(CONFIG_USB_SERIAL_METRO) += metro-usb.o
obj-$(CONFIG_USB_SERIAL_MOS7720) += mos7720.o
obj-$(CONFIG_USB_SERIAL_MOS7840) += mos7840.o
obj-$(CONFIG_USB_SERIAL_MXUPORT) += mxuport.o
obj-$(CONFIG_USB_SERIAL_NAVMAN) += navman.o
obj-$(CONFIG_USB_SERIAL_OMNINET) += omninet.o
obj-$(CONFIG_USB_SERIAL_OPTICON) += opticon.o
obj-$(CONFIG_USB_SERIAL_OPTION) += option.o
obj-$(CONFIG_USB_SERIAL_OTI6858) += oti6858.o
obj-$(CONFIG_USB_SERIAL_PL2303) += pl2303.o
obj-$(CONFIG_USB_SERIAL_QCAUX) += qcaux.o
obj-$(CONFIG_USB_SERIAL_QUALCOMM) += qcserial.o
obj-$(CONFIG_USB_SERIAL_QT2) += quatech2.o
obj-$(CONFIG_USB_SERIAL_SAFE) += safe_serial.o
obj-$(CONFIG_USB_SERIAL_SIERRAWIRELESS) += sierra.o
obj-$(CONFIG_USB_SERIAL_SIMPLE) += usb-serial-simple.o
obj-$(CONFIG_USB_SERIAL_SPCP8X5) += spcp8x5.o
obj-$(CONFIG_USB_SERIAL_SSU100) += ssu100.o
obj-$(CONFIG_USB_SERIAL_SYMBOL) += symbolserial.o
obj-$(CONFIG_USB_SERIAL_WWAN) += usb_wwan.o
obj-$(CONFIG_USB_SERIAL_TI) += ti_usb_3410_5052.o
obj-$(CONFIG_USB_SERIAL_VISOR) += visor.o
obj-$(CONFIG_USB_SERIAL_WISHBONE) += wishbone-serial.o
obj-$(CONFIG_USB_SERIAL_WHITEHEAT) += whiteheat.o
obj-$(CONFIG_USB_SERIAL_XIRCOM) += keyspan_pda.o
obj-$(CONFIG_USB_SERIAL_XSENS_MT) += xsens_mt.o

So, can i compile this make file?

Note that option.c is NOT in that Makefile. So while you can compile that, it's not going to make any difference considering the source you modified is not in that particular module.

option.c file is inside the serial folder. I edited this file.

Make file speaks about
obj-$(CONFIG_USB_SERIAL_OPTION) += option.o

What is this?

You're right, I missed that. I actually searched for option.c not option.o.

If you have the capabilities to make the modules properly set up then yes, you can just run that particular makefile to build just that module.

Thanks, i will try this let you know.

Thanks you.

I edited the option.c and
did this module build from the folder /drivers/usb/serial
ARCH=arm CROSS_COMPILE=${CCPREFIX} make

root@mars:/home/mars/Raspberry-Dev/linux/drivers/usb/serial# ARCH=arm CROSS_COMPILE=${CCPREFIX} make
make: *** No targets. Stop.

mars@mars:~/Raspberry-Dev/linux/drivers/usb/serial$ ARCH=arm CROSS_COMPILE=${CCPREFIX} make
make: *** No targets. Stop.

i try ed with as root and as user
Any problem in Makefile? or commands?

followed http://sysprogs.com/VisualKernel/tut...y/buildkernel/

Looks like step #9 would build the kernel and modules together. And then in step #11 you would install the modules to the correct target directory structure prior to copying it over to the Pi target. Therefore your changes should have been compiled if you followed that entirely. Considering that they have it all combined into the one make procedure, I'd use the "Contact" link they have on that site and ask if they know how to just build only the modules, and only a particular module sub-directory. You may also wish to retry step #9 with the qualifier: "make modules" and see if that makes just the modules and not the kernel. Further, another thing to try might be to give the proper subdirectory when invoking that make, such as "make drivers/usb/serial" to see if it will build just that set of drivers. But obviously invoke it from the top kernel level.

Try ed all the ways still flashing errors.

Contacted the support team, told to follow http://sysprogs.com/VisualKernel/tut...y/basicmodule/

step 5: is optional? I could not find the config.gz from the Linux folder.

step 5
scp pi@raspberrypi:/proc/config.gz .
ssh: connect to host raspberrypi port 22: Connection timed out