From: Paolo Bonzini <pbonzini@redhat.com>
To: Victor Kamensky <victor.kamensky@linaro.org>,
Alexander Graf <agraf@suse.de>,
Christoffer Dall <christoffer.dall@linaro.org>
Cc: kvm-devel <kvm@vger.kernel.org>,
kvm-ppc <kvm-ppc@vger.kernel.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>
Subject: Re: [RFC PATCH] KVM: Specify byte order for KVM_EXIT_MMIO
Date: Fri, 24 Jan 2014 15:32:45 +0000 [thread overview]
Message-ID: <52E2879D.6070609@redhat.com> (raw)
In-Reply-To: <CAA3XUr0_odUuMWOsCP-n9FH6L2emzfYeisT81v_FMoo9voK-mQ@mail.gmail.com>
Il 24/01/2014 16:23, Victor Kamensky ha scritto:
> Also if you use ints on real bus as description, you may want to clarify
> restrictions on mmio.len. Basically on 32 bit platform (i.e like V7
> ARM) one cannot have mmio.len=8, because one cannot have 64bit
> value on 32bit data bus. Without such clarification introduction of
> text like "the value as it would go on the bus in real hardware" is
> confusing for len=8 for emulated CPUs where real busses are
> 32bit.
This is not necessarily true. On a 32-bit CPU you can have a 64-bit
memory bus. Even x86 32-bit CPUs can do 64-bit MMIO via MMX or SSE or
double-word compare-and-swap (CMPXCHG8B).
Paolo
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Victor Kamensky <victor.kamensky@linaro.org>,
Alexander Graf <agraf@suse.de>,
Christoffer Dall <christoffer.dall@linaro.org>
Cc: kvm-devel <kvm@vger.kernel.org>,
kvm-ppc <kvm-ppc@vger.kernel.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>
Subject: Re: [RFC PATCH] KVM: Specify byte order for KVM_EXIT_MMIO
Date: Fri, 24 Jan 2014 16:32:45 +0100 [thread overview]
Message-ID: <52E2879D.6070609@redhat.com> (raw)
In-Reply-To: <CAA3XUr0_odUuMWOsCP-n9FH6L2emzfYeisT81v_FMoo9voK-mQ@mail.gmail.com>
Il 24/01/2014 16:23, Victor Kamensky ha scritto:
> Also if you use ints on real bus as description, you may want to clarify
> restrictions on mmio.len. Basically on 32 bit platform (i.e like V7
> ARM) one cannot have mmio.len=8, because one cannot have 64bit
> value on 32bit data bus. Without such clarification introduction of
> text like "the value as it would go on the bus in real hardware" is
> confusing for len=8 for emulated CPUs where real busses are
> 32bit.
This is not necessarily true. On a 32-bit CPU you can have a 64-bit
memory bus. Even x86 32-bit CPUs can do 64-bit MMIO via MMX or SSE or
double-word compare-and-swap (CMPXCHG8B).
Paolo
next prev parent reply other threads:[~2014-01-24 15:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-23 23:46 [RFC PATCH] KVM: Specify byte order for KVM_EXIT_MMIO Christoffer Dall
2014-01-23 23:46 ` Christoffer Dall
2014-01-24 0:01 ` Peter Maydell
2014-01-24 13:09 ` Paolo Bonzini
2014-01-24 13:09 ` Paolo Bonzini
2014-01-24 13:13 ` Alexander Graf
2014-01-24 13:13 ` Alexander Graf
2014-01-24 15:23 ` Victor Kamensky
2014-01-24 15:23 ` Victor Kamensky
2014-01-24 15:32 ` Paolo Bonzini [this message]
2014-01-24 15:32 ` Paolo Bonzini
2014-01-24 16:19 ` Victor Kamensky
2014-01-24 16:19 ` Victor Kamensky
2014-01-24 16:34 ` Victor Kamensky
2014-01-24 16:34 ` Victor Kamensky
2014-01-24 19:17 ` Victor Kamensky
2014-01-24 19:17 ` Victor Kamensky
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