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

2019-06-21 Thread Launchpad Bug Tracker
[Expired for QEMU because there has been no activity for 60 days.] ** Changed in: qemu Status: Incomplete => Expired -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1824768 Title: Qemu ARMv7

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

2019-04-22 Thread TimeMaster
>> ./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

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

2019-04-21 Thread Richard Henderson
** Changed in: qemu Status: New => Incomplete -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1824768 Title: Qemu ARMv7 TCG MultiThreading for i386 guest doesn't work Status in QEMU: Incomp

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

2019-04-21 Thread Richard Henderson
When you say > ./qemu-system-i386 -cdrom alpine.iso --accel tcg,thread=multi you have not created multiple cpus for the guest, so thread=multi should have no effect. For what it's worth, a boot of debian-9.8.0-i386-netinst.iso (which is what I happened to have handy) works fine with ./qemu-s

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

2019-04-16 Thread TimeMaster
Interesting, maybe that is the reason why it is not restricted to use mttcg from the command line. So I will be waiting here if you need :) -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1824768 Titl

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

2019-04-16 Thread Peter Maydell
That patch is already in QEMU (commit b32dc3370a666e23). It sounds like we're a bit further forward with this than I thought we might be, but clearly not everything necessary is implemented. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to Q

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

2019-04-16 Thread TimeMaster
Yes, I can imagine that. Unfortunately, my programming knowledge isn't so strong to help you with it. But can help with testing if it is useful. Alex Bennée pointed me to this patch: [RFC,v3,4/5] mttcg: Implement implicit ordering semantics Which maybe could help. I can try to compile it and do

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

2019-04-16 Thread Peter Maydell
Implementing a stronger guest memory model than the host has is tricky -- we would need to emit barrier instructions after each guest load or store, which would slow down straight-line execution speed by quite a lot, perhaps by so much that it would outweigh the gain from being able to run more tha

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

2019-04-16 Thread 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

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

2019-04-16 Thread Peter Maydell
This is expected. The warning from QEMU is telling you that MTTCG is not supported for the combination of an Arm host and an x86 guest. It warns that you might see "strange errors", and indeed you saw an error. Don't try to use MTTCG here. I think this warning should probably just be an error -- Q