From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=42848 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OgZZo-0006it-3I for qemu-devel@nongnu.org; Wed, 04 Aug 2010 04:43:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OgZZl-00029M-VJ for qemu-devel@nongnu.org; Wed, 04 Aug 2010 04:43:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12140) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OgZZl-00029G-OW for qemu-devel@nongnu.org; Wed, 04 Aug 2010 04:43:49 -0400 Date: Wed, 4 Aug 2010 11:43:42 +0300 From: Gleb Natapov Subject: Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35? Message-ID: <20100804084342.GB10499@redhat.com> References: <4C5858B2.9090801@redhat.com> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C592218.3000901@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Gerd Hoffmann , "Richard W.M. Jones" On Wed, Aug 04, 2010 at 11:17:28AM +0300, Avi Kivity wrote: > On 08/04/2010 10:56 AM, Gerd Hoffmann wrote: > > Hi, > > > >>>(1) -M somethingold. PCI devices don't have a pci rom bar then by > >>>default because they didn't not have one in older qemu versions, > >>>so we need some other way to pass the option rom to seabios. > >> > >>What did we do back then? before we had the fwcfg interface? > > > >Have qemu instead of bochs/seabios manage the vgabios/optionrom > >area (0xc8000 -> 0xe0000) and copy the roms to memory. Which > >implies the whole rom has to sit there as PMM can't be used then. > > Do we actually need PMM for isapc? Did PMM exist before pci? > > > > >>>(3) roms not associated with a PCI device: multiboot, extboot, > >>>-option-rom command line switch, vgabios for -M isapc. > >> > >>We could lay those out in high memory (4GB-512MB) and have the bios copy > >>them from there. > > > >Yea, we could. But it is pointless IMHO. > > > >$ ls -l *.bin > >-rwxrwxr-x. 1 kraxel kraxel 1536 Jul 15 15:51 extboot.bin* > >-rwxrwxr-x. 1 kraxel kraxel 1024 Jul 15 15:51 linuxboot.bin* > >-rwxrwxr-x. 1 kraxel kraxel 1024 Jul 15 15:51 multiboot.bin* > >-rwxrwxr-x. 1 kraxel kraxel 8960 Jul 15 15:51 vapic.bin* > > > >That are the ones we can't load via pci rom bar. Look how small > >they are. > > So they can just sit there? I'm confused, either there is enough > address space and we don't need to play games, or there isn't and we > do. > > 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. > We can do interface like that: guest enumerates available roms using fwcfg. Guest can tell host to map rom into guest specified IOMEM region. Guest copies rom from IOMEM region and tell host to unmap it. -- Gleb.