From: Marcelo Tosatti <mtosatti@redhat.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: kvm-devel <kvm@vger.kernel.org>, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: KVM: x86: workaround SuSE's 2.6.16 pvclock vs masterclock issue
Date: Wed, 21 Jan 2015 12:16:34 -0200 [thread overview]
Message-ID: <20150121141634.GB718@amt.cnet> (raw)
In-Reply-To: <20150121140926.GA9085@potion.brq.redhat.com>
On Wed, Jan 21, 2015 at 03:09:27PM +0100, Radim Krčmář wrote:
> 2015-01-20 15:54-0200, Marcelo Tosatti:
> > SuSE's 2.6.16 kernel fails to boot if the delta between tsc_timestamp
> > and rdtsc is larger than a given threshold:
> [...]
> > Disable masterclock support (which increases said delta) in case the
> > boot vcpu does not use MSR_KVM_SYSTEM_TIME_NEW.
>
> Why do we care about 2.6.16 bugs in upstream KVM?
Because people do use 2.6.16 guests.
> The code to benefit tradeoff of this patch seems bad to me ...
Can you state the tradeoff and then explain why it is bad ?
> MSR_KVM_SYSTEM_TIME is deprecated -- we could remove it now, with
> MSR_KVM_WALL_CLOCK (after hiding KVM_FEATURE_CLOCKSOURCE) if we want
> to support old guests.
What is the benefit of removing support for MSR_KVM_SYSTEM_TIME ?
Supporting old guests is important.
next prev parent reply other threads:[~2015-01-21 14:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-20 17:54 KVM: x86: workaround SuSE's 2.6.16 pvclock vs masterclock issue Marcelo Tosatti
2015-01-20 19:40 ` Paolo Bonzini
2015-01-21 14:09 ` Radim Krčmář
2015-01-21 14:16 ` Marcelo Tosatti [this message]
2015-01-21 17:00 ` Radim Krčmář
2015-01-22 1:40 ` Marcelo Tosatti
2015-01-22 13:59 ` Radim Krčmář
2015-01-22 18:12 ` Marcelo Tosatti
2015-01-22 19:33 ` Radim Krčmář
2015-01-22 8:10 ` Paolo Bonzini
2015-01-22 17:02 ` Radim Krčmář
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