From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55656) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aluhS-0001fr-H4 for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:45:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aluhP-0008Ve-7g for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:45:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49922) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aluhP-0008Va-23 for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:44:59 -0400 Date: Fri, 1 Apr 2016 09:44:56 +0100 From: "Richard W.M. Jones" Message-ID: <20160401084456.GF32728@redhat.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56FE3045.2030003@redhat.com> Subject: Re: [Qemu-devel] Why is SeaBIOS used with -kernel? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: marc.mari.barcelo@gmail.com, Stefan Hajnoczi , Kevin O'Connor , qemu-devel@nongnu.org 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? Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org