lunix headers not found

[xavfa]

Dear all,
I encountered an issue while simply using the make function. but as I searched quite a lot of internet pages I didn't clearly found the solution.
here is the message while trying the make function :
make -C /usr/src/linux-headers-4.14.79-v7+ M=/home/pi/soft_uart modules
make[1]: *** /usr/src/linux-headers-4.14.79-v7+ : Aucun fichier ou dossier de ce type. Arrêt.
Makefile:9 : la recette pour la cible « all » a échouée
make: *** [all] Erreur 2

mu pi is on Raspbian GNU/LINUX 9.6.
the available headers are
linux-headers-3.10-3-all linux-headers-3.6-trunk-rpi
linux-headers-3.10-3-all-armhf linux-headers-4.4.0-1-all
linux-headers-3.10-3-common linux-headers-4.4.0-1-all-armhf
linux-headers-3.10-3-rpi linux-headers-4.4.0-1-common
linux-headers-3.16.0-4-all linux-headers-4.4.0-1-rpi
linux-headers-3.16.0-4-all-armhf linux-headers-4.4.0-1-rpi2
linux-headers-3.16.0-4-common linux-headers-4.9.0-6-all
linux-headers-3.16.0-4-rpi linux-headers-4.9.0-6-all-armhf
linux-headers-3.18.0-trunk-all linux-headers-4.9.0-6-common
linux-headers-3.18.0-trunk-all-armhf linux-headers-4.9.0-6-common-rt
linux-headers-3.18.0-trunk-common linux-headers-4.9.0-6-rpi
linux-headers-3.18.0-trunk-rpi linux-headers-4.9.0-6-rpi2
linux-headers-3.18.0-trunk-rpi2 linux-headers-rpi
linux-headers-3.6-trunk-all linux-headers-rpi2
linux-headers-3.6-trunk-all-armhf linux-headers-rpi2-rpfv
linux-headers-3.6-trunk-common linux-headers-rpi-rpfv

there is not the required one and I didn't any way with update action to fix it...
I really need to get extra Tx/RX pins. the existing one are already used...
please, any idea ??
many thank
xavier

[biplabro]

Hi,
I have encountered the same issue. Hope you have solved the problem by now, if not then please follow the below steps. For some unexplained reason the /usr/src directory did not contain the existing running rpi kernel sources.

here is the work around.

1. update your pi firmware
   --- sudo rpi-update

2. update rpi system
   --- sudo apt update && sudo apt upgrade

3. install the kernel headers
   --- sudo apt-get install raspberrypi-kernel-headers

goto the soft_uart directory & hit 'make'
magically the problem will be solved. I got mine fixed that way. Hope it helps.

pi@raspberrypi:~/soft_uart-master $ ls /dev | grep ttyS
ttyS0
ttySOFT0
pi@raspberrypi:~/soft_uart-master $