From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=38599 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Ogdgh-0005fo-A0 for qemu-devel@nongnu.org; Wed, 04 Aug 2010 09:07:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1Ogdgf-0001sf-AS for qemu-devel@nongnu.org; Wed, 04 Aug 2010 09:07:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:5496) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1Ogdgf-0001sY-0b for qemu-devel@nongnu.org; Wed, 04 Aug 2010 09:07:13 -0400 Date: Wed, 4 Aug 2010 16:07:09 +0300 From: Gleb Natapov Subject: Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35? Message-ID: <20100804130709.GL10499@redhat.com> References: <4C585F5B.5070502@codemonkey.ws> <4C58635B.7020407@redhat.com> <20100803190525.GB16570@redhat.com> <4C586AB9.5040302@codemonkey.ws> <4C586CF9.7030206@redhat.com> <4C588804.5060803@redhat.com> <4C590046.2020705@redhat.com> <4C591D48.9080301@redhat.com> <4C592218.3000901@redhat.com> <4C596549.1070109@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C596549.1070109@codemonkey.ws> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: qemu-devel@nongnu.org, "Richard W.M. Jones" , Avi Kivity , kvm@vger.kernel.org, Gerd Hoffmann On Wed, Aug 04, 2010 at 08:04:09AM -0500, Anthony Liguori wrote: > On 08/04/2010 03:17 AM, Avi Kivity wrote: > >For playing games, there are three options: > >- existing fwcfg > >- fwcfg+dma > >- put roms in 4GB-2MB (or whatever we decide the flash size is) > >and have the BIOS copy them > > > >Existing fwcfg is the least amount of work and probably > >satisfactory for isapc. fwcfg+dma is IMO going off a tangent. > >High memory flash is the most hardware-like solution, pretty easy > >from a qemu point of view but requires more work. > > The only trouble I see is that high memory isn't always available. > If it's a 32-bit PC and you've exhausted RAM space, then you're only > left with the PCI hole and it's not clear to me if you can really > pull out 100mb of space there as an option ROM without breaking > something. > We can map it on demand. Guest tells qemu to map rom "A" to address X by writing into some io port. Guest copies rom. Guest tells qemu to unmap it. Better then DMA interface IMHO. -- Gleb.