[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device

From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device
Date: Mon, 08 Mar 2010 15:16:11 +0200
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20100301 Fedora/3.0.3-1.fc12 Thunderbird/3.0.3

On 03/08/2010 03:03 PM, Paul Brook wrote:
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.

Ah yes. For cross tcg environments you can map the memory using mmio callbacks instead of directly, and issue the appropriate barriers there.

error compiling committee.c: too many arguments to function

reply via email to

[Prev in Thread] Current Thread [Next in Thread]