I am new to linux and I really need your help
I am working on project for my end of studies internship : controlling sensors and displaying the result on an LCD screen
for that I will use raspberry and create a QT application for displaying the result of the sensors.
The boot time needs to be very minimal (maximum 20s) so for that I want to create a minimal kernel for my raspberri pi-4 b
sudo apt install git bc bison flex libssl-dev make libc6-dev libncurses5-dev sudo apt install crossbuild-essential-arm64 git clone --depth=1 https://github.com/raspberrypi/linux cd linux/ export KERNEL=kernel8 make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bcm2711_defconfig make -j8 ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- Image modules dtbs mkdir mnt mkdir mnt/fat32 mkdir mnt/ext4 sudo mount /dev/mmcblk0p1 mnt/fat32 sudo mount /dev/mmcblk0p2 mnt/ext4 sudo env PATH=$PATH make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- INSTALL_MOD_PATH=mnt/ext4 modules_install sudo cp mnt/fat32/kernel8.img mnt/fat32/kernel8-backup.img
these are the steps that I followed but I got an error
cp: cannot stat 'mnt/fat32/kernel8.img': No such file or directory
$ sudo cp arch/arm64/boot/dts/overlays/*.dtb* mnt/fat32/overlays/ cp: target 'mnt/fat32/overlays/' is not a directory
so I tried to create it
$ mkdir mnt/fat32/overlays mkdir: cannot create directory ‘mnt/fat32/overlays’: Permission denied
can anyone please help me I am stuck in this error for 2 weeks now and I need to build my kernel to start working on it!
I don't know also if this version of kernel and this configuration are minimal. can I have a minimal boot time with this configuration (I think of changing the boot sequence and just enable the devices needed for my application at first but of course i don't know how to do it) If anyone can help please en-light me !! even if you just know a good tutoriel to recommand me or something..
I will be grateful if someone could help