From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH] kvm tools: adds a PCI device that exports a host shared
 segment as a PCI BAR in the guest
Date: Fri, 26 Aug 2011 00:11:03 +0300
Message-ID: <4E56BA67.9000901@redhat.com>
References: <20110824222510.GC14835@dancer.ca.sandia.gov> <232C9ABA-F703-4AE5-83BC-774C715D4D8F@suse.de> <20110825044913.GA24996@dancer.ca.sandia.gov> <1314248794.32391.60.camel@jaguar> <CAJSP0QVB-7Bncx8K4udnC=BZq1994u44_8t0rddFDMQaHYLH7Q@mail.gmail.com> <CAOJsxLFDg+xZ0=eDC5NkAAPNf71nSXYQvYfe2jSRr9p=dE4wEQ@mail.gmail.com> <CAJSP0QW3SWDtq_CJzohQ+xz66OkD1ABsYM4scnp2YTmDVsONKg@mail.gmail.com> <1314271548.3692.22.camel@lappy> <30669_1314285268_p7PFESZN013126_20110825150806.GF24996@dancer.ca.sandia.gov> <20110825210018.GA27983@dancer.ca.sandia.gov>
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Cc: Sasha Levin <levinsasha928@gmail.com>,
	Stefan Hajnoczi <stefanha@gmail.com>,
	Pekka Enberg <penberg@kernel.org>,
	Alexander Graf <agraf@suse.de>, kvm@vger.kernel.org,
	cam@cs.ualberta.ca
To: David Evensky <evensky@dancer.ca.sandia.gov>
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On 08/26/2011 12:00 AM, David Evensky wrote:
> I've tested ivshmem with the latest git pull (had minor trouble
> building on debian sid, vnc and unused var, but trivial to work
> around).
>
> QEMU's  -device ivshmem,size=16,shm=/kvm_shmem
>
> seems to function as my proposed
>
>          --shmem pci:0xfd000000:16M:handle=/kvm_shmem
>
> except that I can't specify the BAR. I am able to read what
> I'm given, 0xfd000000, from lspci -vvv; but for our application
> we need to be able to specify the address on the command line.
>
> If folks are open, I would like to request this feature in the
> ivshmem.

It's not really possible. Qemu does not lay out the BARs, the guest does 
(specifically the bios).  You might be able to re-arrange the layout 
after the guest boots.

Why do you need the BAR at a specific physical address?

> It would be cool to test our application with QEMU,
> even if we can't use it in production.

Why can't you use qemu in production?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.