From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=42668 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OgMrW-0001uv-5D for qemu-devel@nongnu.org; Tue, 03 Aug 2010 15:09:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OgMrU-0003j6-7z for qemu-devel@nongnu.org; Tue, 03 Aug 2010 15:09:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12345) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OgMrT-0003iq-W9 for qemu-devel@nongnu.org; Tue, 03 Aug 2010 15:09:16 -0400 Message-ID: <4C586951.7000808@redhat.com> Date: Tue, 03 Aug 2010 22:09:05 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35? References: <20100803162857.GX13789@amd.home.annexia.org> <4C584781.9040609@redhat.com> <4C5847CD.9080107@codemonkey.ws> <4C5848C7.3090806@redhat.com> <4C584982.5000108@codemonkey.ws> <4C584B66.5070404@redhat.com> <4C5854F1.3000905@codemonkey.ws> <4C5858B2.9090801@redhat.com> <4C585F5B.5070502@codemonkey.ws> <4C58635B.7020407@redhat.com> <20100803190525.GB16570@redhat.com> In-Reply-To: <20100803190525.GB16570@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: kvm@vger.kernel.org, "Richard W.M. Jones" , qemu-devel@nongnu.org On 08/03/2010 10:05 PM, Gleb Natapov wrote: > >> That's true, but extending fwcfg doesn't fit into the overall >> picture well. We have well defined interfaces for pushing data into >> a guest: virtio-serial (dma upload), virtio-blk (adds demand >> paging), and virtio-p9fs (no image needed). Adapting libguestfs to >> use one of these is a better move than adding yet another interface. >> > +1. I already proposed that. Nobody objects against fast fast > communication channel between guest and host. In fact we have one: > virtio-serial. Of course it is much easier to hack dma semantic into > fw_cfg interface than add virtio-serial to seabios, but it doesn't make > it right. Does virtio-serial has to be exposed as PCI to a guest or can > we expose it as ISA device too in case someone want to use -kernel option > but do not see additional PCI device in a guest? No need for virtio-serial in firmware. We can have a small initrd slurp a larger filesystem via virtio-serial, or mount a virtio-blk or virtio-p9fs, or boot the whole thing from a virtio-blk image and avoid -kernel -initrd completely. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.