linux kernel - trying to cross compile on ubuntu (for rpi zero)

[fresh virtual box vm, using ubuntu 20.04, all updates made during install]

I just try to run make bcmrpi_defconfig on a linux kernel git repository

patched for RT :

wget
zcat patch-4.19.127-rt55.patch.gz | patch -p1

but it say it cannot find the arm compiler...

phil@rt-linux-pi:~/linux$ /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc
bash: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian
/bin/arm-linux-gnueabihf-gcc: No such file or directory
phil@rt-linux-pi:~/linux$ ls /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc -lha
lrwxrwxrwx 1 phil phil 29 Jun 25 22:58 /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc -> arm-linux-gnueabihf-gcc-4.8.3

I now realize arm-linux-gnueabihf-gcc is nowhere to be found on the system

I get this error :

make bcmrpi_defconfig
/bin/sh: 1: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
/bin/sh: 1: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
./scripts/gcc-version.sh: 26: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
./scripts/gcc-version.sh: 27: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
./scripts/gcc-version.sh: 29: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
./scripts/gcc-version.sh: 26: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
./scripts/gcc-version.sh: 27: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
./scripts/gcc-version.sh: 29: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
init/Kconfig:17: syntax error
init/Kconfig:16: invalid option
./scripts/clang-version.sh: 15: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
./scripts/gcc-plugin.sh: 11: /home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: not found
make[1]: *** [scripts/kconfig/Makefile:104: bcmrpi_defconfig] Error 1
make: *** [Makefile:534: bcmrpi_defconfig] Error 2

I tried :

• installing build essentials

• I installed these packages : libncurses-dev flex bison openssl libssl-dev dkms libelf-dev libudev-dev libpci-dev libiberty-dev autoconf

• I moded the PATH variable :

echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/phil/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/

thanks for the time you'll spend on this question

regards

I follow this tutorial :

1 Answer

the official doc explains things a bit better and in a more "recent way" of doing things

first mod and source .bashrc file and add at the end :

if [ -d "$HOME/tools/arm-bcm2708/arm-linux-gnueabihf/bin" ] ; then PATH="$PATH:$HOME/tools/arm-bcm2708/arm-linux-gnueabihf/bin"
fi

to build kernel do :

sudo apt install git bc bison flex libssl-dev make libc6-dev libncurses5-dev
git clone --depth=1 --branch rpi-4.19.y
cd linux
export KERNEL=kernel
make bcmrpi_defconfig
cd ..
git clone ~/tools
cd linux
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcmrpi_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs

hope this helps someone else too