From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Evensky Subject: Re: [PATCH] kvm tools: adds a PCI device that exports a host shared segment as a PCI BAR in the guest Date: Wed, 24 Aug 2011 21:49:13 -0700 Message-ID: <20110825044913.GA24996@dancer.ca.sandia.gov> References: <20110824222510.GC14835@dancer.ca.sandia.gov> <232C9ABA-F703-4AE5-83BC-774C715D4D8F@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Evensky , penberg@kernel.org, Sasha Levin , kvm@vger.kernel.org To: Alexander Graf Return-path: Received: from sentry-two.sandia.gov ([132.175.109.14]:48305 "EHLO sentry-two.sandia.gov" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751701Ab1HYEtS (ORCPT ); Thu, 25 Aug 2011 00:49:18 -0400 Content-Disposition: inline In-Reply-To: <232C9ABA-F703-4AE5-83BC-774C715D4D8F@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Aug 24, 2011 at 10:27:18PM -0500, Alexander Graf wrote: > > On 24.08.2011, at 17:25, David Evensky wrote: > > > > > > > This patch adds a PCI device that provides PCI device memory to the > > guest. This memory in the guest exists as a shared memory segment in > > the host. This is similar memory sharing capability of Nahanni > > (ivshmem) available in QEMU. In this case, the shared memory segment > > is exposed as a PCI BAR only. > > > > A new command line argument is added as: > > --shmem pci:0xc8000000:16MB:handle=/newmem:create > > > > which will set the PCI BAR at 0xc8000000, the shared memory segment > > and the region pointed to by the BAR will be 16MB. On the host side > > the shm_open handle will be '/newmem', and the kvm tool will create > > the shared segment, set its size, and initialize it. If the size, > > handle, or create flag are absent, they will default to 16MB, > > handle=/kvm_shmem, and create will be false. The address family, > > 'pci:' is also optional as it is the only address family currently > > supported. Only a single --shmem is supported at this time. > > Did you have a look at ivshmem? It does that today, but also gives you an IRQ line so the guests can poke each other. For something as simple as this, I don't see why we'd need two competing implementations. Isn't ivshmem in QEMU? If so, then I don't think there isn't any competition. How do you feel that these are competing? \dae > > > Alex > >