<!-- This is the upstream QEMU issue tracker. If you are able to, it will greatly facilitate bug triage if you attempt to reproduce the problem with the latest qemu.git master built from source. See https://www.qemu.org/download/#source for instructions on how to do this. QEMU generally supports the last two releases advertised on https://www.qemu.org/. Problems with distro-packaged versions of QEMU older than this should be reported to the distribution instead. See https://www.qemu.org/contribute/report-a-bug/ for additional guidance. If this is a security issue, please consult https://www.qemu.org/contribute/security-process/ --> ## Host environment - Operating system: Rocky Linux 8.10 <!-- Windows 10 21H1, Fedora 37, etc. --> - OS/kernel version: Linux 4.18.0-553.el8_10.x86_64 <!-- For POSIX hosts, use `uname -a` --> - Architecture: x86 <!-- x86, ARM, s390x, etc. --> - QEMU flavor: qemu-system-arm <!-- qemu-system-x86_64, qemu-aarch64, qemu-img, etc. --> - QEMU version: QEMU emulator version 11.0.50 (v11.0.0-3079-g191489ba75-dirty) <!-- e.g. `qemu-system-x86_64 --version` --> ## Emulated/Virtualized environment - Operating system: none <!-- Windows 10 21H1, Fedora 37, etc. --> - OS/kernel version: none <!-- For POSIX guests, use `uname -a`. --> - Architecture: ARM <!-- x86, ARM, s390x, etc. --> ## Description of problem <!-- Describe the problem, including any error/crash messages seen. --> I tried running uboot on some ARM boards. Use migration during the uboot phase. After migration, unable to re-enter the interaction environment of uboot normally. ## Steps to reproduce 1. git clone https://github.com/u-boot/u-boot.git u-boot commit 501d76ca801343cce6dafb17740a8b679ed17072 ``` $ export ARCH=arm $ export CROSS_COMPILE=arm-linux-gnueabihf- $ make imx_v6_v7_defconfig $ make ``` 2. compile qemu ``` $ mkdir build && cd build $ ../configure --target-list="aarch64-softmmu,arm-softmmu" --disable-slirp --enable-debug --disable-werror ``` 3. run qemu and enter qemu monitor(ctrl + a + c) ``` ./build/qemu-system-arm -M sabrelite -smp 4 -m 1G -display none -serial null -serial mon:stdio -kernel ~/u-boot/u-boot U-Boot 2026.07-rc4-g1e80ee41441c (Jul 15 2026 - 14:34:41 +0800) ... scanning usb for storage devices... 0 Storage Device(s) found Hit any key to stop autoboot: 0 => QEMU 11.0.50 monitor - type 'help' for more information (qemu) migrate -d file:vmstate (qemu) q ``` 4. migration, but can not enter u-boot ``` ./build/qemu-system-arm -M sabrelite -smp 4 -m 1G -display none -serial null -serial mon:stdio -kernel ~/u-boot/u-boot --incoming file:vmstate QEMU 11.0.50 monitor - type 'help' for more information (qemu) info status VM status: running (qemu) info migrate Status: completed ``` ## Additional information I add some log in target/arm/machine.c cpu_pre_save() and cpu_post_load() ``` qemu_log("pc=%08x cpsr=%08x scr=%08x " "sctlr_s=%08" PRIx64 " sctlr_ns=%08" PRIx64 " " "ttbr0_s=%" PRIx64 " ttbr0_ns=%" PRIx64 " " "dacr_s=%08" PRIx64 " dacr_ns=%08" PRIx64 " " "vbar_s=%08" PRIx64 " vbar_ns=%08" PRIx64 " " "ifsr_s=%08" PRIx64 " ifsr_ns=%08" PRIx64 " " "ifar_s=%08x ifar_ns=%08x\n", env->regs[15], env->uncached_cpsr, (uint32_t)env->cp15.scr_el3, env->cp15.sctlr_s, env->cp15.sctlr_ns, env->cp15.ttbr0_s, env->cp15.ttbr0_ns, env->cp15.dacr_s, env->cp15.dacr_ns, env->cp15.vbar_s, env->cp15.vbar_ns, env->cp15.ifsr_s, env->cp15.ifsr_ns, env->cp15.ifar_s, env->cp15.ifar_ns); ``` ``` arm mig pre_save: pc=4efa12f2 cpsr=00000013 scr=00000000 sctlr_s=00c5187d sctlr_ns=00c50078 ttbr0_s=4fff0059 ttbr0_ns=0 dacr_s=55555555 dacr_ns=00000000 vbar_s=4ef77000 vbar_ns=00000000 ``` But after migration. ``` arm mig post_load: pc=4efa12f2 cpsr=00000013 scr=00000000 sctlr_s=00c5187d sctlr_ns=00c50078 ttbr0_s=4fff0059 ttbr0_ns=0 dacr_s=00000000 dacr_ns=00000000 vbar_s=4ef77000 vbar_ns=00000000 ifsr_s=00000000 ifsr_ns=00000000 ifar_s=00000000 ifar_ns=00000000 ``` It seems that some register values have not been restored. The same problem also occurs on xilinx-zynq-a9 and vexpress-a9, it seems that they both use Cortex-A9. Use different config when compiling uboot: zynq_zc702_defconfig,vexpress_ca9x4_defconfig. launch qemu command: ``` ./build/qemu-system-aarch64 -M xilinx-zynq-a9 -machine boot-mode=sd -m 1024 -display none -serial null -serial mon:stdio -device loader,file=~/u-boot/u-boot-dtb.bin,addr=0x04000000,cpu-num=0 -D qemu.log ./build/qemu-system-arm -M vexpress-a9,secure=on -nographic -kernel ~/u-boot/u-boot ``` <!-- Attach logs, stack traces, screenshots, etc. Compress the files if necessary. If using libvirt, libvirt logs and XML domain information may be relevant. --> <!-- The line below ensures that proper tags are added to the issue. Please do not remove it. -->