From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56094) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1alujq-0002th-5x for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:47:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1alujm-0000Uy-U8 for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:47:30 -0400 Received: from mail-wm0-x22a.google.com ([2a00:1450:400c:c09::22a]:36755) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1alujm-0000Un-ND for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:47:26 -0400 Received: by mail-wm0-x22a.google.com with SMTP id 127so12080621wmu.1 for ; Fri, 01 Apr 2016 01:47:26 -0700 (PDT) Sender: Paolo Bonzini References: <20160319203124.GB19398@redhat.com> <20160331092125.GH32185@stefanha-x1.localdomain> <20160331162222.GA17533@morn.lan> <20160331221039.GA32728@redhat.com> <20160331221730.GA5637@redhat.com> <20160331224432.GA4583@morn.lan> <20160401080222.GC32728@redhat.com> <56FE2D42.5020607@redhat.com> <20160401081417.GD32728@redhat.com> <56FE3045.2030003@redhat.com> <20160401084456.GF32728@redhat.com> From: Paolo Bonzini Message-ID: <56FE3599.3010401@redhat.com> Date: Fri, 1 Apr 2016 10:47:21 +0200 MIME-Version: 1.0 In-Reply-To: <20160401084456.GF32728@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Why is SeaBIOS used with -kernel? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Richard W.M. Jones" Cc: marc.mari.barcelo@gmail.com, Stefan Hajnoczi , Kevin O'Connor , qemu-devel@nongnu.org On 01/04/2016 10:44, Richard W.M. Jones wrote: > On Fri, Apr 01, 2016 at 10:24:37AM +0200, Paolo Bonzini wrote: >> On 01/04/2016 10:14, Richard W.M. Jones wrote: >>> Found it: only CONFIG_MPTABLE=y was necessary. It boots with: >>> >>> # CONFIG_PIRTABLE is not set >>> CONFIG_MPTABLE=y >>> # CONFIG_SMBIOS is not set >>> # CONFIG_ACPI is not set >> >> If you add all three it should not give any slowdown and will provide >> full hardware features to the kernel. qboot does ACPI and PCI bus >> assignment (it doesn't do SMBIOS because I got bored debugging it. :)) > > Enabling all 4 adds about 2ms. > > However the overhead of SeaBIOS is still down from 68ms to 18ms > (4.0% of total boot time down to 1.1%) so it's still a big gain. > > I wonder how we can make use of this in qemu and downstream distros? > Can we have a bios-min.bin which is used with -kernel boots? That's an interesting idea. We can look at it for 2.7. Paolo