Re: Conflicting parameters on qemu call

On 21. Aug 2020, at 11:20, Daniel P. Berrangé <berrange(a)redhat.com&gt; wrote: > On Fri, Aug 21, 2020 at 11:19:14AM +0200, Jan Walzer wrote: >> Hi Daniel, >>> On 21. Aug 2020, at 11:07, Daniel P. Berrangé <berrange(a)redhat.com&gt; wrote: >>> On Fri, Aug 21, 2020 at 11:00:27AM +0200, Jan Walzer wrote: >>>> On 21. Aug 2020, at 10:38, Daniel P. Berrangé <berrange(a)redhat.com&gt; wrote: >>>>> On Thu, Aug 20, 2020 at 08:11:30PM +0200, Jan Walzer wrote: >>>>>> Hi Lists, >>>>>> >>>>>> I currently have the issue of wanting to use emu-system-x86_64 on a ppc64le platform. >>>>>> >>>>>> It is imperative to pass the "-accel tcg,thread=multi” parameter to qemu >>>>>> when starting an instance, as without that, it will only use one thread >>>>>> and hence of limited/no use. >>>>>> >>>>>> The problem is, that libvirt itself, passes “-machine q35,accel=tcg” to >>>>>> qemu, which is a different parameter, that conflicts with the other one. >>>>>> >>>>>> Can we discuss, if I either have overlooked something, or is there a workaround, or is this a bug? >>>>> >>>>> What you're trying todo is intentionally not available. >>>>> >>>>> The memory ordering constraints needed for running x86_64 guests on ppc64 >>>>> hosts cannot be satisfied, so multi-threaded TCG is not available. >>>>> >>>>> For any guest/host combination where multi-thread TCG is safe to use, QEMU >>>>> will enable it automatically, so nothing is required in libvirt. >>>> >>>> >>>> Hi Daniel, >>>> Thanks for the answer. I’ve read (and understand) the warnings and their implications. >>>> >>>> So there’s not even an “I know what I’m Doing”-Switch? >>> >>> […] >>> <qemu:commandline> >>> <qemu:arg value='-accel'/> >>> <qemu:arg value='tcg,thread=multi'/> >>> </qemu:commandline> >> >> As I wrote: This is what I’m already doing >> The Problem is that this conflicts with, libvirt already using the parameter: “-machine ..,accel=tcg” >> And I can’t get libvirt, to stop passing this parameter. > > It shouldn't matter. QEMU should aggregate the settings from the > multiple args, with latter args overriding earlier args if there is > any duplication.. That was what I thought to, but: # qemu-system-x86_64 -machine q35,accel=tcg -accel tcg,thread=multi --smp 8 -m 8 Unable to init server: Could not connect: Connection refused qemu-system-x86_64: The -accel and "-machine accel=" options are incompatible # qemu-system-x86_64 --version QEMU emulator version 5.0.0 (Debian 1:5.0-14) Copyright (c) 2003-2020 Fabrice Bellard and the QEMU Project developers I’m already discussing that on qemu list: https://lists.nongnu.org/archive/html/qemu-ppc/2020-08/msg00338.html <https://lists.nongnu.org/archive/html/qemu-ppc/2020-08/msg00338.html> But I’d like to track that issue in multiple directions.