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#1 2025-07-01 14:06:56
- ktauchathuranga
- Member
- Registered: 2025-05-25
- Posts: 8
trying to build an minimal UEFI os but failing in VGA output
hi,
i am prettty new to this,
i just wanna create simple minimal UEFI linux os with busybox, so i can boot it to my pendrive and launch in my laptop,
but i am unable to get the output to the VGA.
i can get the nomrmal os output to the console, but in vga, i cant get the output to show.
i am using an Dell laptop if it relevant.
i will attach ss's and the my build script as well.
help would be much appreciated. 
#!/bin/bash
# Exit immediately if a command exits with a non-zero status.
set -e
# --- Configuration ---
OS_NAME="PrivilegeOS"
KERNEL_VER="6.15.3"
BUSYBOX_VER="1.36.1"
# Source directories (assumed to be in the same folder as the script)
SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
KERNEL_SRC_DIR="${SCRIPT_DIR}/linux-${KERNEL_VER}"
BUSYBOX_SRC_DIR="${SCRIPT_DIR}/busybox-${BUSYBOX_VER}"
# Build directory
BUILD_DIR="${SCRIPT_DIR}/build"
INITRAMFS_DIR="${BUILD_DIR}/initramfs"
USB_MNT_DIR="${BUILD_DIR}/usbmnt" # Mount point for USB flashing
DISK_IMG="${BUILD_DIR}/${OS_NAME}.img"
# This variable will be set later if we use a loop device
LOOP_DEV=""
# --- Helper Functions ---
log() {
echo -e "\n\e[1;32m[INFO] ==> $1\e[0m"
}
error() {
echo -e "\n\e[1;31m[ERROR] ==> $1\e[0m"
exit 1
}
warn() {
echo -e "\n\e[1;33m[WARNING] ==> $1\e[0m"
}
cleanup() {
log "Cleaning up..."
# Unmount USB mount point if it exists
if mountpoint -q "${USB_MNT_DIR}"; then
sudo umount "${USB_MNT_DIR}"
fi
# Detach loop device if it was used
if [ -n "$LOOP_DEV" ] && losetup -a | grep -q "${LOOP_DEV}"; then
sudo umount "${BUILD_DIR}/mnt" || true
sudo losetup -d "${LOOP_DEV}" || true
fi
}
trap cleanup EXIT
usage() {
echo "Usage: $0 [action] [device]"
echo "Actions:"
echo " run Builds the disk image and runs it in QEMU. (Default)"
echo " build Builds the disk image and exits."
echo " usb <device> Builds and flashes the OS to a USB device (e.g., /dev/sdc)."
echo " !!! THIS IS DESTRUCTIVE AND WILL ERASE THE DEVICE !!!"
exit 1
}
# --- Main Build Steps ---
check_dependencies() {
log "Checking for dependencies..."
# Added wipefs for cleaner partitioning
local deps=("gcc" "make" "bc" "ncursesw6-config" "qemu-system-x86_64" "parted" "mkfs.vfat" "losetup" "wipefs")
for dep in "${deps[@]}"; do
if ! command -v "$dep" &> /dev/null; then
error "Dependency '$dep' not found. Please install it."
fi
done
if [ ! -f /usr/share/ovmf/x64/OVMF.fd ]; then
error "OVMF firmware not found at /usr/share/ovmf/x64/OVMF.fd. Please install the 'ovmf' package. The path might also be 'OVMF_CODE.fd' on some systems."
fi
log "All dependencies are satisfied."
}
setup_workspace() {
log "Setting up the build workspace..."
if [ ! -d "$KERNEL_SRC_DIR" ]; then
error "Kernel source directory not found: $KERNEL_SRC_DIR"
fi
if [ ! -d "$BUSYBOX_SRC_DIR" ]; then
error "BusyBox source directory not found: $BUSYBOX_SRC_DIR"
fi
rm -rf "$BUILD_DIR"
mkdir -p "$BUILD_DIR"
mkdir -p "${INITRAMFS_DIR}"/{bin,sbin,etc,proc,sys,dev,usr/bin,usr/sbin}
log "Workspace created at ${BUILD_DIR}"
}
build_busybox() {
log "Building BusyBox..."
cd "$BUSYBOX_SRC_DIR"
make distclean
make defconfig
# Statically link BusyBox to avoid library dependencies
sed -i 's/# CONFIG_STATIC is not set/CONFIG_STATIC=y/' .config
# This can sometimes cause build issues, disabling if not needed.
sed -i 's/^CONFIG_TC=y/# CONFIG_TC is not set/' .config
make -j$(nproc)
make CONFIG_PREFIX="${INITRAMFS_DIR}" install
cd "$SCRIPT_DIR"
log "BusyBox build complete."
}
create_initramfs_content() {
log "Creating initramfs content..."
sudo mknod -m 622 "${INITRAMFS_DIR}/dev/console" c 5 1
sudo mknod -m 666 "${INITRAMFS_DIR}/dev/null" c 1 3
sudo mknod -m 666 "${INITRAMFS_DIR}/dev/zero" c 1 5
cat <<EOF > "${INITRAMFS_DIR}/init"
#!/bin/sh
mount -t proc none /proc
mount -t sysfs none /sys
mount -t devtmpfs none /dev
exec /sbin/init
EOF
chmod +x "${INITRAMFS_DIR}/init"
cat <<EOF > "${INITRAMFS_DIR}/etc/inittab"
::sysinit:/etc/init.d/rcS
tty1::askfirst:-/bin/sh
ttyS0::askfirst:-/bin/sh
::restart:/sbin/init
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::shutdown:/sbin/swapoff -a
EOF
mkdir -p "${INITRAMFS_DIR}/etc/init.d"
cat <<EOF > "${INITRAMFS_DIR}/etc/init.d/rcS"
#!/bin/sh
echo ""
echo " ____ _ _ _ _ ___ ____ "
echo " | _ \ _ __(_) | | _ __ (_) / _ \/ ___| "
echo " | |_) | '__| | | | | '_ \| |/ / | \___ \ "
echo " | __/| | | | | |_| |_) | / /| |___) |"
echo " |_| |_| |_|_|\___/ .__/|_\/ \____/ "
echo " |_| "
echo ""
echo "Welcome to ${OS_NAME}! Type 'poweroff' or 'reboot' to exit."
echo ""
hostname -F /etc/hostname
EOF
chmod +x "${INITRAMFS_DIR}/etc/init.d/rcS"
echo "${OS_NAME}" > "${INITRAMFS_DIR}/etc/hostname"
log "initramfs content created."
}
# --- FIXED build_kernel FUNCTION ---
build_kernel() {
log "Building the Linux Kernel..."
cd "$KERNEL_SRC_DIR"
make mrproper
make defconfig
# --- QEMU Specific Drivers (Keep them for testing) ---
./scripts/config --enable CONFIG_VIRTIO_PCI
./scripts/config --enable CONFIG_VIRTIO_BLK
./scripts/config --enable CONFIG_VIRTIO_CONSOLE
./scripts/config --enable CONFIG_DRM_VIRTIO_GPU
# --- Core UEFI/Boot Requirements (Correct) ---
./scripts/config --enable CONFIG_EFI_STUB
./scripts/config --enable CONFIG_EFI
./scripts/config --enable CONFIG_FB_EFI
./scripts/config --enable CONFIG_DEVTMPFS
./scripts/config --enable CONFIG_DEVTMPFS_MOUNT
./scripts/config --enable CONFIG_FRAMEBUFFER_CONSOLE
./scripts/config --enable CONFIG_LOGO
./scripts/config --enable CONFIG_LOGO_LINUX_CLUT224
# --- Core Console/Serial (Correct) ---
./scripts/config --enable CONFIG_SERIAL_8250
./scripts/config --enable CONFIG_SERIAL_8250_CONSOLE
# --- Generic Drivers for Real Hardware (Good start) ---
./scripts/config --enable CONFIG_SATA_AHCI # SATA disks
./scripts/config --enable CONFIG_USB_XHCI_HCD # USB 3.0
./scripts/config --enable CONFIG_USB_EHCI_HCD # USB 2.0
./scripts/config --enable CONFIG_USB_OHCI_HCD # USB 1.1
./scripts/config --enable CONFIG_USB_HID # Keyboards, Mice
./scripts/config --enable CONFIG_HID_GENERIC
./scripts/config --enable CONFIG_E1000E # Common Intel NIC
./scripts/config --enable CONFIG_SND_HDA_INTEL # Common Intel HD Audio
# ====================================================================
# --- Drivers for Real Physical GPUs (FIXED) ---
# ====================================================================
log "Enabling drivers for physical GPUs..."
# Enable the main DRM (Direct Rendering Manager) subsystem
./scripts/config --enable CONFIG_DRM
./scripts/config --enable CONFIG_DRM_KMS_HELPER
# Enable Intel i915 Driver (Most common for Dell laptops)
./scripts/config --enable CONFIG_DRM_I915
# The i915 driver may need firmware (see explanation below)
./scripts/config --enable CONFIG_DRM_I915_CAPTURE_ERROR
# --- FIX: Force probe i915 devices even if firmware is missing ---
./scripts/config --enable CONFIG_DRM_I915_FORCE_PROBE
./scripts/config --set-str CONFIG_DRM_I915_FORCE_PROBE "\"*\""
# Ensure firmware loader is built-in (might help if we have firmware)
./scripts/config --enable CONFIG_FW_LOADER
./scripts/config --enable CONFIG_FW_LOADER_BUILTIN
# (Optional but Recommended) Enable AMD GPU Driver for wider compatibility
./scripts/config --enable CONFIG_DRM_AMD
./scripts/config --enable CONFIG_DRM_AMDGPU
# --- Initramfs config (Correct) ---
./scripts/config --enable CONFIG_INITRAMFS_SOURCE
./scripts/config --set-str CONFIG_INITRAMFS_SOURCE "${INITRAMFS_DIR}"
# --- Command line (Correct) ---
./scripts/config --enable CONFIG_CMDLINE_BOOL
# Using a more verbose command line for debugging on real hardware
./scripts/config --set-str CONFIG_CMDLINE "console=tty1 console=ttyS0,115200 loglevel=7"
make olddefconfig
make -j$(nproc) bzImage
cd "$SCRIPT_DIR"
log "Kernel build complete. Ready at ${KERNEL_SRC_DIR}/arch/x86/boot/bzImage"
}
install_to_uefi_target() {
local TARGET_DEV="$1"
local TARGET_IS_BLOCKDEV=false
if [ -b "${TARGET_DEV}" ]; then
TARGET_IS_BLOCKDEV=true
fi
if [ "$TARGET_IS_BLOCKDEV" = true ]; then
log "Preparing to flash to block device ${TARGET_DEV}"
warn "THIS WILL COMPLETELY ERASE ALL DATA ON ${TARGET_DEV}."
echo -e "\n\e[1;33mDevice information:\e[0m"
lsblk -o NAME,SIZE,MODEL "${TARGET_DEV}"
read -p $'\n\e[1;31mARE YOU ABSOLUTELY SURE? Type YES to continue: \e[0m' CONFIRMATION
if [ "${CONFIRMATION}" != "YES" ]; then
error "Aborted by user."
fi
log "User confirmed. Wiping and partitioning ${TARGET_DEV}..."
sudo umount "${TARGET_DEV}"* || true
sudo wipefs -a "${TARGET_DEV}"
else
log "Creating UEFI disk image file..."
dd if=/dev/zero of="${TARGET_DEV}" bs=1M count=256
fi
sudo parted -s "${TARGET_DEV}" mklabel gpt
sudo parted -s "${TARGET_DEV}" mkpart ESP fat32 1MiB 100%
sudo parted -s "${TARGET_DEV}" set 1 esp on
if [ "$TARGET_IS_BLOCKDEV" = true ]; then
log "Waiting for kernel to recognize new partition..."
sleep 3
sudo partprobe "${TARGET_DEV}"
sleep 1
fi
local PARTITION
if [ "$TARGET_IS_BLOCKDEV" = true ]; then
# This logic handles both standard devices (sda -> sda1)
# and NVMe devices (nvme0n1 -> nvme0n1p1).
if [[ "${TARGET_DEV}" == *nvme* ]]; then
PARTITION="${TARGET_DEV}p1"
else
PARTITION="${TARGET_DEV}1"
fi
else
# This is the logic for file-based images
LOOP_DEV=$(sudo losetup -f --show -P "${TARGET_DEV}")
if [ -z "$LOOP_DEV" ]; then
error "Failed to set up loopback device."
fi
PARTITION="${LOOP_DEV}p1"
fi
if [ ! -b "$PARTITION" ]; then
error "Could not find partition device at '${PARTITION}'. The kernel may not have detected it."
fi
log "Formatting partition ${PARTITION} as FAT32..."
sudo mkfs.vfat -F 32 "${PARTITION}"
log "Mounting and copying EFI bootloader..."
local MNT_POINT
if [ "$TARGET_IS_BLOCKDEV" = true ]; then
MNT_POINT="${USB_MNT_DIR}"
else
MNT_POINT="${BUILD_DIR}/mnt"
fi
mkdir -p "${MNT_POINT}"
sudo mount "${PARTITION}" "${MNT_POINT}"
sudo mkdir -p "${MNT_POINT}/EFI/BOOT"
sudo cp "${KERNEL_SRC_DIR}/arch/x86/boot/bzImage" "${MNT_POINT}/EFI/BOOT/BOOTX64.EFI"
log "Unmounting target..."
sudo umount "${MNT_POINT}"
if [ "$TARGET_IS_BLOCKDEV" = false ]; then
sudo losetup -d "${LOOP_DEV}"
else
sync
fi
log "UEFI target ${TARGET_DEV} is ready."
}
run_qemu() {
log "Starting QEMU..."
qemu-system-x86_64 \
-machine q35,accel=kvm \
-cpu host \
-m 2G \
-smp 2 \
-bios /usr/share/ovmf/x64/OVMF.4m.fd \
-drive file="${DISK_IMG}",format=raw,if=virtio \
-device intel-hda -device hda-output \
-nic user,model=e1000e \
-device usb-ehci -device usb-tablet \
-serial stdio \
-no-reboot
}
# --- Main Execution Flow ---
main() {
ACTION="${1:-run}" # Default to 'run' if no action is specified
case "$ACTION" in
run)
# check_dependencies
# setup_workspace
# build_busybox
# create_initramfs_content
# build_kernel
install_to_uefi_target "${DISK_IMG}"
run_qemu
;;
build)
setup_workspace
build_busybox
create_initramfs_content
build_kernel
install_to_uefi_target "${DISK_IMG}"
log "Build complete. Image is at ${DISK_IMG}"
;;
usb)
TARGET_USB_DEV="$2"
if [ -z "$TARGET_USB_DEV" ]; then
error "No target device specified for 'usb' action."
usage
fi
if [ ! -b "$TARGET_USB_DEV" ]; then
error "Target '${TARGET_USB_DEV}' is not a block device."
fi
# check_dependencies
setup_workspace
build_busybox
create_initramfs_content
build_kernel
install_to_uefi_target "${TARGET_USB_DEV}"
log "Flashing complete. You can now safely eject ${TARGET_USB_DEV} and boot from it."
;;
*)
usage
;;
esac
log "Done."
}
main "$@"Offline
#2 2025-07-02 21:40:44
- unixman
- Member
- Registered: 2015-03-12
- Posts: 182
Re: trying to build an minimal UEFI os but failing in VGA output
UEFI dont support VGA when booting as native.(no CMS).
you have to resort GOP. (graphics output protocol: an UEFI thingie:)
Offline