Hello all, Really strange thing happening here.. I can't see the full stack trace with 'bt' command in gdb. So I tried with fresh linux-5.10.122 source and qemu-6.2.0 source and it's happening too! (it's happening when I do combinations with linux 5.10.0 and qemu-5.1.0. But it's not happening with linux-5.4.21) I would be grateful if somebody could check if this happens to other people or just me. 1. download linux-5.1.122 tarball from https://www.kernel.org/ 2. uncompress it and set env variable ARCH=arm64, CROSS_COMPILE=aarch64-none-elf- , do "make defconfig" and "make -j`nproc` Image" 3. download qemu-6.2.0 from https://www.qemu.org/ 4. uncompress it and do "mkdir build" "cd build" "../configure --target-list=aarch64-softmmu --enable-debug" 5. run qemu and wait for debugger to attach. qemu-6.2.0/build/aarch64-softmmu/qemu-system-aarch64 -machine virt,gic-version=max,secure=off,virtualization=true -cpu max -kernel linux-5.10.112/arch/arm64/boot/Image -m 2G -nographic -netdev user,id=vnet,hostfwd=:127.0.0.1:0-:22,tftp=/srv/tftp -device virtio-net-pci,netdev=vnet -machine iommu=smmuv3 --append "root=/dev/ram init=/init nokaslr earlycon ip=dhcp hugepages=16" -s -S 6. run debugger, do "aarch64-none-elf-gdb linux-6.10.112/vmlinux -x gdb_script" (gdb_script content : target remote :1234 layout src b start_kernel b __driver_attach ) Now, in gdb, when you press 'c' twice, it'll stop at the first __driver_attach. (first one stops at start_kernel). When you are at __attach_driver, type 'bt'. See if you see the full function stack trace. This is what I see. (gdb) bt #0 __driver_attach (dev=0xffff000002582810, data=0xffff800011dc2358 <dummy_regulator_driver+40>) at drivers/base/dd.c:1060 #1 0xffff8000107a3ed0 in bus_for_each_dev (bus=<optimized out>, start=<optimized out>, data=0xffff800011dc2358 <dummy_regulator_driver+40>, fn=0xffff8000107a6f60 <__driver_attach>) at drivers/base/bus.c:305 #2 0xd6d78000107a5c58 in ?? () Backtrace stopped: previous frame identical to this frame (corrupt stack?) I used to see more thatn 20 stacks trace but strangely I see only two. I can still see many stacks for linux-5.4.21 that I was working with in the past. Could anyone check if this happens to anyone? I think if I add BLK_DEV_RAM and set initramfs.cpio.gz in the linux build, the kernel will boot ok to the shell prompt. Only the gdb can't show the stack levels. My OS : ubuntu-20.04 5.13.0-35-generic $ aarch64-none-elf-gdb --version GNU gdb (GNU Toolchain for the A-profile Architecture 10.2-2020.11 (arm-10.16)) 10.1.90.20201028-git Copyright (C) 2020 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Thank you. Chan Kim