semantic: 0.191
graphic: 0.188
other: 0.104
vnc: 0.094
device: 0.091
performance: 0.049
permissions: 0.045
network: 0.045
PID: 0.040
socket: 0.040
boot: 0.034
debug: 0.031
files: 0.025
KVM: 0.022
debug: 0.721
performance: 0.114
files: 0.034
other: 0.024
device: 0.016
PID: 0.015
KVM: 0.015
semantic: 0.012
boot: 0.012
socket: 0.009
network: 0.008
graphic: 0.007
permissions: 0.006
vnc: 0.005

VFP code cannot see CPACR write in the same TB

If FPU is enabled by writing to CPACR, and the code is in the same translation block as the following VFP code, qemu generates "v7M NOCP UsageFault".

This can be reproduced with git HEAD (commit 8fe9f1f891eff4e37f82622b7480ee748bf4af74).

The target binary is attached. The qemu command is:
qemu-system-arm -nographic -monitor null -serial null -semihosting -machine mps2-an505 -cpu cortex-m33 -kernel cpacr_vfp.elf -d in_asm,int,exec,cpu,cpu_reset,unimp,guest_errors,nochain -D log

If the code is changed a little, so that they are not in the same block, VFP code can see the effect of CPACR, or -singlestep of qemu has the same result.



Sorry, it's because a "ISB" is missing after CPACR is changed. Not bug of qemu.