[Qemu-devel] [Bug 1824768] Re: Qemu ARMv7 TCG MultiThreading for i386 guest doesn't work

[TimeMaster <timemaster@trillinis.com>]

>> ./qemu-system-i386 -cdrom alpine.iso --accel tcg,thread=multi

I tried both, with -smp 4 and without..

In stable Qemu release, there is just a guest kernel panic, in
v4.0.0-rc3-dirty, there is also Illegal instruction error reported

> on an x-gene system, compiled for aarch32.
Yes, this should be Raspberry Pi 3, but I am not sure. Anyway, I can test this in one week when I receive one of those boards.

>Just so we're clear, which raspberry pi revision are you using?
>Based on comments I'm assuming pi 2, with the 4 core cortex-a7.

I am using Raspberry Pi 2, 4 cores, not sure where is the difference
between cortex-a7 and ARMv7, in my case it is just ARMv7.

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https://bugs.launchpad.net/bugs/1824768

Title:
  Qemu ARMv7 TCG MultiThreading for i386 guest doesn't work

Status in QEMU:
  Incomplete

Bug description:
  Using any Linux image (in this case Alpine Linux iso) I want to
  utilise all cores of my Raspberry with --accel,thread=multi. I know
  there is a probably still problem with memory ordering of the host,
  but I have also seen some very old commits which could potentially
  help with it.

  But anyway, with version qemu-i386 version 3.1.0 (Debian 1:3.1+dfsg-7)
  I can see OpenRC starting up services and then the kernel crash.

  With version QEMU emulator version 3.1.93 (v4.0.0-rc3-dirty)
  The whole machine crash with this error:
  Illegal instruction

  Using command:
  ./qemu-system-i386 -cdrom alpine.iso --accel tcg,thread=multi

  Full Console Output:
  qemu-system-i386: warning: Guest expects a stronger memory ordering than the host provides
  This may cause strange/hard to debug errors
  Illegal instruction

  Kernel:
  Linux raspberrypi 4.14.98-v7+ #1200 SMP Tue Feb 12 20:27:48 GMT 2019 armv7l GNU/Linux

  CPU:
  ARMv7 Processor rev 5 (v7l)
  Features: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
  4 cores

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