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

[TimeMaster]

Thank you for the explanation. I found some patches a few years old, so
I thought the implementation is now complete especially when ARM is
getting more and more popular.

Does it have some priority assigned? Or does it even make sense to do
it? From my perspective, yes even with the broken support the whole boot
process was blazingly fast on Raspberry and seemed that kernel was able
to start and then crashed. Even this was so fast compared to one core.
It's interesting there are no more people wanting this. Maybe I am
missing another trend :)

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

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

Status in QEMU:
  New

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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