From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eduardo Habkost <ehabkost@redhat.com>
Subject: Re: [libvirt] [RFC] kvm: x86: export vCPU halted state to sysfs
Date: Fri, 2 Feb 2018 15:42:49 -0200
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Cc: Peter Krempa <pkrempa@redhat.com>, kvm@vger.kernel.org,
	Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
	libvir-list@redhat.com, Luiz Capitulino <lcapitulino@redhat.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>, pbonzini@redhat.com
To: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
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On Fri, Feb 02, 2018 at 05:19:34PM +0100, Viktor Mihajlovski wrote:
> On 02.02.2018 17:01, Luiz Capitulino wrote:
[...]
> >  o Make qemuDomainRefreshVcpuHalted() s390-only in libvirt. This by
> >    itself fixes the original performance issue
> We are normally trying to avoid architecture-specific code in libvirt
> (not always successfully). We could omit the call, based on a QEMU
> Capability derived from the presence of said flag. This would change the
> libvirt-client side default to not report halted. A client can the still
> request the value via a tbd libvirt flag. Which is what an s390-aware
> management app would have to do...

The problem I see here is that the current semantics of the
"halted" field in QEMU is arch-specific, so either libvirt or
upper layers will necessarily need arch-specific code if they
want to support QEMU 2.11 or older.

-- 
Eduardo