From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45676) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhHFn-0000Sf-A9 for qemu-devel@nongnu.org; Tue, 06 Sep 2016 10:21:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bhHFi-0004nL-7Q for qemu-devel@nongnu.org; Tue, 06 Sep 2016 10:21:35 -0400 Received: from mail-wm0-x241.google.com ([2a00:1450:400c:c09::241]:34389) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhHFi-0004nB-0X for qemu-devel@nongnu.org; Tue, 06 Sep 2016 10:21:30 -0400 Received: by mail-wm0-x241.google.com with SMTP id w12so9305022wmf.1 for ; Tue, 06 Sep 2016 07:21:29 -0700 (PDT) Sender: Paolo Bonzini References: <1472120105-29235-1-git-send-email-chao.p.peng@linux.intel.com> <1473158937.4143.15.camel@linux.intel.com> From: Paolo Bonzini Message-ID: <5fd6c789-4524-0254-6f18-2ec330acec61@redhat.com> Date: Tue, 6 Sep 2016 16:21:25 +0200 MIME-Version: 1.0 In-Reply-To: <1473158937.4143.15.camel@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC PATCH v2 00/12] Guest startup time optimization List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Chao Peng , qemu-devel@nongnu.org Cc: Haozhong Zhang , Xiao Guangrong , Eduardo Habkost , "Michael S. Tsirkin" , gor Mammedov , Amnon Ilan , Richard Henderson On 06/09/2016 12:48, Chao Peng wrote: >> As you might expect, I don't agree with removing the >> firmware. There's >> room for much more optimization before duplicating firmware code in >> QEMU. I'd rather see numbers for: >> >> 1) qboot optimizations: adopt the fw_cfg DMA interface instead of the >> cbfs flash hack (so that -kernel works), drop PCI bridge >> initialization, copy less than 64K of memory from ROM to 0xf0000; > > I can do the evaluation on qboot. Also adding Amnon Ilan, to see if > there is some thing we can do for SeaBios. For SeaBIOS we can try dropping PAM and PCI, but not much more. I've pushed fw_cfg DMA support and some PAM optimizations to qboot (it doesn't setup PAM if QEMU doesn't configure 0xf0000-0x100000 as ROM). I've left it for you to figure out which parts of PCI initialization can be removed. >> 2) Linux optimizations: using an uncompressed image to avoid the >> cost of copying and decompressing. QEMU can already load the image >> at the right place and the real mode stub can do little more than >> GDT/IDT setup. > > This works surely. I actually followed your suggestion in v1 to make > kernel multiboot-compatible and then load that kernel in QEMU directly Please try posting the multiboot patches to the upstream x86 Linux mailing list. I am very interested in them, because I think it's the simplest way to compare qboot with direct kernel load. And as you say, it might make patch 11 a little smaller and possibly more acceptable. Paolo