Build Linux kernel#

download kernel#

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if [[ $(echo $VERSION | cut -d'.' -f3) == '0' ]]; then
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    VERSION=$(echo $VERSION| cut -d'.' -f1,2)
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fi
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# Get the major version number (e.g., '6' from '6.5.3')
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MAJOR_VERSION=$(echo "$VERSION" | cut -d'.' -f1)
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wget "https://cdn.kernel.org/pub/linux/kernel/v${MAJOR_VERSION}.x/linux-${VERSION}.tar.xz"
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tar -xf "linux-${VERSION}.tar.xz"

menuconfig for debug#

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make mrproper && make menuconfig

Kernel hacking#

printk and dmesg options#

Enable core function if dynamic debug support
Enable dynamic printk() support

Compile-time checks and compiler options#

Provide GDB scripts for kernel debugging (CONFIG_GDB_SCRIPTS)
Generate readable assembler code (CONFIG_READABLE_ASM)
one of Debug information
Enable full Section mismatch analysis (IMPORTANT FOR DEBUGGING FUNCTION LIKE handle_pte_fault)

Memory Management options#

Multi-Gen LRU(all selected)
Enable userfaultfd() system call

Build linux kernel and boot using QEMU#

build linux kernel

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export CC='ccache gcc'
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export HOSTCC='ccache gcc'
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make all -j$(nproc)
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make scripts_gdb

if you want to boot new kernel in PC

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export INSTALLKERNEL=installkernel
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KERNEL_NAME=smth
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PRESET_NAME=smth

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sudo make modules_install -j$(nproc)
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sudo make headers_install -j$(nproc)
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sudo make install -j$(nproc)
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sudo cp arch/x86_64/boot/bzImage /boot/vmlinuz-linux-$KERNEL_NAME
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# install dkms
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sudo dkms autoinstall -k $(make kernelrelease)
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# install initramfs via mkinitcpio
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sudo mkinitcpio -p linux-$PRESET_NAME -k $(make kernelrelease)

Build rootfs via busybox#

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git clone https://git.busybox.net/busybox && cd busybox
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# remember to unselect tc in Networking Utilities in menuconfig
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# and use static binary (enable in Settings)
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make mrproper && make menuconfig
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make install -j$(nproc)
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cd _install
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mkdir -p lib lib64 proc sys etc etc/init.d
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# write init script
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touch etc/init.d/rcS
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chmod +x etc/init.d/rcS
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(cat <<EOF
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#!/bin/sh
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# Mount the /proc and /sys filesystems
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mount -t proc none /proc
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mount -t sysfs none /sys
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mount -t devtmpfs none /dev
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mount -t debugfs none /sys/kernel/debug
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# Populate /dev
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/sbin/mdev -s
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EOF
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) > etc/init.d/rcS
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# pack all busybox file into rootfs via cpio and gzip
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find . | cpio -o --format=newc | gzip > ../../rootfs.gz

Boot using QEMU

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qemu-system-x86_64 \
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    -kernel arch/x86_64/boot/bzImage \
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    -nographic \
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    -initrd rootfs.gz \
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    -append "root=/dev/ram rdinit=/sbin/init console=ttyS0"
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    # -S -s // add these flag for gdb debug
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    # add this flag for share directory with host
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    # -virtfs local,id=shared,path=shared,mount_tag=shared,security_model=none

Tracing and debug kernel

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gdb vmlinux -ex 'target remote:1234' -ex 'b start_kernel' -ex 'c'

Build rootfs via pacstrap#

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mkdir rootfs
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sudo chown root:root rootfs
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sudo pacstrap -c ./rootfs base systemd bash
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dd if=/dev/zero of=arch.img bs=1M count=20480
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mkfs.ext4 arch.img
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mkdir mnt
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sudo mount arch.img mnt
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sudo cp -a rootfs/. mnt/
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sudo umount mnt

Boot

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qemu-system-x86_64 \
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    -kernel arch/x86_64/boot/bzImage \
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    -nographic \
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    -drive file=arch.img,format=raw,if=virtio \
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    -m 1G \
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    -append "root=/dev/vda rw console=ttyS0"
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  # -cpu host -enable-kvm -smp $(nproc)

c8763yee's website

Build Linux kernel#

download kernel#

menuconfig for debug#

Kernel hacking#

printk and dmesg options#

Compile-time checks and compiler options#

Memory Management options#

Build linux kernel and boot using QEMU#

Build rootfs via busybox#

Build rootfs via pacstrap#

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c8763yee's website

Build Linux kernel#

download kernel#

menuconfig for debug#

Kernel hacking#

printk and dmesg options#

Compile-time checks and compiler options#

Memory Management options#

Build linux kernel and boot using QEMU#

Build rootfs via busybox#

Build rootfs via pacstrap#

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