From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52442) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1am0Wo-00042b-Kk for qemu-devel@nongnu.org; Fri, 01 Apr 2016 10:58:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1am0Wj-0007ar-Mj for qemu-devel@nongnu.org; Fri, 01 Apr 2016 10:58:26 -0400 Received: from mail-qk0-x231.google.com ([2607:f8b0:400d:c09::231]:34520) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1am0Wj-0007aj-EX for qemu-devel@nongnu.org; Fri, 01 Apr 2016 10:58:21 -0400 Received: by mail-qk0-x231.google.com with SMTP id r184so4368780qkc.1 for ; Fri, 01 Apr 2016 07:58:21 -0700 (PDT) Date: Fri, 1 Apr 2016 10:58:19 -0400 From: Kevin O'Connor Message-ID: <20160401145819.GA25490@morn.lan> References: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160401084456.GF32728@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: "Richard W.M. Jones" Cc: marc.mari.barcelo@gmail.com, Paolo Bonzini , qemu-devel@nongnu.org, Stefan Hajnoczi On Fri, Apr 01, 2016 at 09:44:56AM +0100, 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. CONFIG_SMBIOS and CONFIG_ACPI only control the legacy internal bios tables. One would disable CONFIG_FW_ROMFILE_LOAD to disable the newer ACPI tables; there is no config option currently to disable the newer smbios tables. These config names are a bit misleading, so they probably should be changed in seabios. I didn't expect disabling the above options to do anything besides reduce the size of the seabios binary, so I'm a bit suprised it saved 2ms. Did you have something on your qemu command-line to avoid generating acpi/smbios tables? -Kevin