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Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device |
Date: |
Mon, 8 Mar 2010 13:03:44 +0000 |
User-agent: |
KMail/1.12.4 (Linux/2.6.32-trunk-amd64; KDE/4.3.4; x86_64; ; ) |
> On 03/08/2010 12:53 AM, Paul Brook wrote:
> >> Support an inter-vm shared memory device that maps a shared-memory
> >> object as a PCI device in the guest. This patch also supports
> >> interrupts between guest by communicating over a unix domain socket.
> >> This patch applies to the qemu-kvm repository.
> >
> > No. All new devices should be fully qdev based.
> >
> > I suspect you've also ignored a load of coherency issues, especially when
> > not using KVM. As soon as you have shared memory in more than one host
> > thread/process you have to worry about memory barriers.
>
> Shouldn't it be sufficient to require the guest to issue barriers (and
> to ensure tcg honours the barriers, if someone wants this with tcg)?.
In a cross environment that becomes extremely hairy. For example the x86
architecture effectively has an implicit write barrier before every store, and
an implicit read barrier before every load.
Paul
- [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, (continued)
- [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Cam Macdonell, 2010/03/05
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Paul Brook, 2010/03/07
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Jamie Lokier, 2010/03/07
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Alexander Graf, 2010/03/08
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Jamie Lokier, 2010/03/08
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Alexander Graf, 2010/03/08
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Anthony Liguori, 2010/03/09
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Paul Brook, 2010/03/08
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Jamie Lokier, 2010/03/09
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Avi Kivity, 2010/03/08
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device,
Paul Brook <=
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Avi Kivity, 2010/03/08
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Jamie Lokier, 2010/03/09
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Anthony Liguori, 2010/03/09
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Avi Kivity, 2010/03/10
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Anthony Liguori, 2010/03/10
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Avi Kivity, 2010/03/10
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Paul Brook, 2010/03/10
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Avi Kivity, 2010/03/11
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Paul Brook, 2010/03/11
- Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device, Jamie Lokier, 2010/03/09