Hello all! This is my first time posting here, but I'll try to provide all the detail I can, and I'm grateful for any advice others have to fix this issue. I've been trying to boot the seL4 Hello World tutorial in QEMU with UEFI support on the x86 platform, with the help of the Grub bootloader. It seems I can load the kernel okay, but an error occurs when the kernel tries to load the rootserver:

seL4 failed assertion 'mods_end_paddr > boot_state.ki_p_reg.end' at /home/fennel/grubbuild/stacktest/sel4-tutorials/kernel/src/arch/x86/kernel/boot_sys.c:452 in function try_boot_sys

From my research, it seems to be happening because grub is loading the rootserver module at a lower address than expected. These two lines from serial output during boot indeed show that the module end address is lower than the kernel end address:

module #0: start=0x751000 end=0x7954c8 size=0x444c8 name='' Kernel loaded to: start=0x100000 end=0xc12000 size=0xb12000 entry=0x100298

When running the same hello world project using ./simulate in the build directory, the rootserver module is placed at a higher address and boots ok:

module #0: start=0xc13000 end=0xc574c8 size=0x444c8 name='images/hello-world-image-x86_64-pc99' Kernel loaded to: start=0x100000 end=0xc12000 size=0xb12000 entry=0x100298

Does anyone know if this is a mistake in how I am compiling and building the project, my QEMU settings, or perhaps an issue with how Grub is handling loading the module? Booting from Grub should be possible in theory (https://docs.sel4.systems/Hardware/IA32.html) so any guidance is appreciated. Thank you! - Fennel STEPS TO REPRODUCE: # Contents of grub.cfg - place in current directory menuentry "Load seL4" --class os { insmod efi_gop insmod efi_uga insmod all_video set root='(hd0,gpt1)' multiboot2 /EFI/BOOT/sel4kernel module2 /EFI/BOOT/sel4rootserver } # End of grub.cfg # Compile Grub 2.06 from source to ./grub-2.06 wget https://ftp.gnu.org/gnu/grub/grub-2.06.tar.gz -O grub.tar.gz # Download grub source tar -xvzf grub.tar.gz -C ./ && rm grub.tar.gz # Unzip and remove original file cd grub-2.06 && ./autogen.sh && ./configure --target=x86_64 --with-platform=efi && make # Configure & compile # Install, configure, and compile hello-world seL4 project to ./sel4-tutorials mkdir sel4-tutorials cd sel4-tutorials repo init -u https://github.com/seL4/sel4-tutorials-manifest # Install tutorials repo sync ./init --plat pc99 --tut hello-world cd hello-world_build cmake -DCMAKE_TOOLCHAIN_FILE=../kernel/gcc.cmake -DKernelHugePage=OFF -G Ninja . # Disable huge page requirement ninja # Create final image as disk.img mkdir EFI EFI/BOOT grub-2.06/grub-mkimage -d grub-2.06/grub-core -o EFI/BOOT/BOOTX64.EFI -O x86_64-efi -p "" configfile fat part_gpt gzio multiboot video efi_gop efi_uga normal chain boot multiboot2 all_video cp sel4-tutorials/hello-world_build/images/kernel-x86_64-pc99 EFI/BOOT/sel4kernel cp sel4-tutorials/hello-world_build/images/hello-world-image-x86_64-pc99 EFI/BOOT/sel4rootserver cp grub.cfg EFI/BOOT/grub.cfg dd if=/dev/zero of=disk.img bs=1M count=35 # 35MB is just about the smallest FAT32 partition possible mformat -i disk.img@@2048s -v "EFI SYSTEM" -F # Create fat32 partition 2048 sectors in mcopy -i disk.img@@2048s -s EFI :: parted -s disk.img mklabel gpt mkpart '"EFI SYSTEM"' fat32 2048s 100% set 1 esp on # Create partition entry for ESP # Run in QEMU (most of these arguments are copied from the seL4 ./simulate script - replace OVMF path with your path to OVMF_CODE.fd for UEFI boot) qemu-system-x86_64 -cpu Nehalem,-vme,+pdpe1gb,-xsave,-xsaveopt,-xsavec,-fsgsbase,-invpcid,+syscall,+lm,enforce -serial mon:stdio -m size=512M -drive if=pflash,format=raw,readonly=on,file=PATH_TO_OVMF_CODE.fd -drive file=disk.img