[Bug 1916112] Re: Illegal instruction crash of QEMU on Jetson Nano

[Peter Maydell]

Now fixed in master, commit d81bad24dfea6ec0

** Changed in: qemu
       Status: Confirmed => Fix Committed

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https://bugs.launchpad.net/bugs/1916112

Title:
  Illegal instruction crash of QEMU on Jetson Nano

Status in QEMU:
  Fix Committed

Bug description:
  I have a jetson nano (arm64 SBC) and I want to check the native
  emulation performance of Raspbian Buster. I used the info available
  here:

  https://github.com/dhruvvyas90/qemu-rpi-kernel/tree/master/native-
  emuation

  I have Xubuntut 20.04 with KVM enabled kernel running on the Jetson
  Nano

  However QEMU crashes with "Illegal Instruction" during kernel boot. I
  have a built latest QEMU from sources with following configuration

  ./configure --prefix=/usr/local --target-list=aarch64-softmmu,arm-
  softmmu  --enable-guest-agent --enable-vnc  --enable-vnc-jpeg
  --enable-vnc-png --enable-kvm --enable-spice --enable-sdl --enable-gtk
  --enable-virglrenderer --enable-opengl

  qemu-system-aarch64 --version
  QEMU emulator version 5.2.50 (v5.2.0-1731-g5b19cb63d9)

  When I run as follows:

  ../build/qemu-system-aarch64 -M raspi3
  -append "rw earlyprintk loglevel=8 console=ttyAMA0,115200 
dwc_otg.lpm_enable=0 root=/dev/mmcblk0p2 rootdelay=1"
  -dtb ./bcm2710-rpi-3-b-plus.dtb
  -sd 
/media/96747D21747D0571/JetsonNano/2020-08-20-raspios-buster-armhf-full.qcow2
  -kernel ./kernel8.img
  -m 1G -smp 4 -serial stdio -usb -device usb-mouse -device usb-kbd

  I get :
  [ 74.994834] systemd[1]: Condition check resulted in FUSE Control File System 
being skipped.
  [ 76.281274] systemd[1]: Starting Apply Kernel Variables...
  Starting Apply Kernel Variables...
  Illegal instruction (core dumped)

  When I use GDB I see this:

  Thread 8 "qemu-system-aar" received signal SIGILL, Illegal instruction.
  [Switching to Thread 0x7fad7f9ba0 (LWP 28037)]
  0x0000007f888ac690 in code_gen_buffer ()
  (gdb) bt
  #0 0x0000007f888ac690 in code_gen_buffer ()
  #1 0x0000005555d7c038 in cpu_tb_exec (tb_exit=, itb=, cpu=0x7fb4502c40)
  at ../accel/tcg/cpu-exec.c:191
  #2 cpu_loop_exec_tb (tb_exit=, last_tb=, tb=, cpu=0x7fb4502c40)
  at ../accel/tcg/cpu-exec.c:708
  #3 cpu_exec (cpu=cpu@entry=0x7fb4502c40) at ../accel/tcg/cpu-exec.c:819
  ..

  I have just two questions:

  Is this a problem with QEMU or is there anything specific build or
  options I need to use. Any specific version of QEMU should be used ?

  Why is TCG used as the accelerator when KVM is present. Is it possible
  and how to use KVM ?

  If I enabled the KVM then I get this error:

  ../build/qemu-system-aarch64 -M raspi3 -enable-kvm -append "rw earlyprintk 
loglevel=8 console=ttyAMA0,115200 dwc_otg.lpm_enable=0 root=/dev/mmcblk0p2 
rootdelay=1" -dtb ./bcm2710-rpi-3-b-plus.dtb -sd 
/media/96747D21747D0571/JetsonNano/2020-08-20-raspios-buster-armhf-full.qcow2 
-kernel ./kernel8.img -m 1G -smp 4 -serial stdio -usb -device usb-mouse -device 
usb-kbd
  WARNING: Image format was not specified for 
'/media/96747D21747D0571/JetsonNano/2020-08-20-raspios-buster-armhf-full.img' 
and probing guessed raw.
           Automatically detecting the format is dangerous for raw images, 
write operations on block 0 will be restricted.
           Specify the 'raw' format explicitly to remove the restrictions.
  qemu-system-aarch64: ../softmmu/physmem.c:750: cpu_address_space_init: 
Assertion `asidx == 0 || !kvm_enabled()' failed.

  Thanks a lot.

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