From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60226) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1anLyw-00059p-9o for qemu-devel@nongnu.org; Tue, 05 Apr 2016 04:05:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1anLys-00018U-6X for qemu-devel@nongnu.org; Tue, 05 Apr 2016 04:05:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36592) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1anLys-00017u-0e for qemu-devel@nongnu.org; Tue, 05 Apr 2016 04:04:58 -0400 Date: Tue, 5 Apr 2016 09:04:55 +0100 From: "Richard W.M. Jones" Message-ID: <20160405080454.GU32728@redhat.com> References: <56FE2D42.5020607@redhat.com> <20160401081417.GD32728@redhat.com> <56FE3045.2030003@redhat.com> <20160401084456.GF32728@redhat.com> <1459502310.7011.37.camel@redhat.com> <20160401101733.GI32728@redhat.com> <1459508875.7011.62.camel@redhat.com> <20160401111139.GK32728@redhat.com> <20160401112027.GD19398@redhat.com> <20160405043836.GB4183@noname.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160405043836.GB4183@noname.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: Kevin Wolf Cc: marc.mari.barcelo@gmail.com, Stefan Hajnoczi , qemu-devel@nongnu.org, Kevin O'Connor , Gerd Hoffmann , Paolo Bonzini On Tue, Apr 05, 2016 at 06:38:36AM +0200, Kevin Wolf wrote: > Am 01.04.2016 um 13:20 hat Richard W.M. Jones geschrieben: > > > > My patch, plus the configuration and comments from your patch, > > combined. Plus I tested it with libguestfs boot-analysis and it works > > and is still fast. > > > > Integrating this so it happens automatically when the user adds > > -kernel on x86 seems quite complicated. The only way I could do it > > was by adding #ifdef defined(__x86_64__) etc to vl.c, which doesn't > > seem very nice. The problem is the machine type code doesn't know > > that you're using -kernel. > > I would actually find it rather surprising to get differernt BIOSes and > therefore potentially different behaviour for -kernel and for booting > from an image. Even if we made sure that Linux really never touches the > parts that you disable in bios-fast.bin, remember that -kernel is not > only for Linux, but for arbitrary kernels. > > Requiring an explicit -bios option like you do now seems to make most > sense to me: The default behaves the same as a normal boot, but if you > are one of the cases that do need that additional boot speed, you can do > that and consciously sacrifice the features. OK so this reminds me of the second problem. How to detect what bioses are available, given a qemu binary. It would be nice if qemu had an option like: qemu -bios \? Of course we can try to scan /usr/share/qemu/bios.*, except that Fedora installs extra ROMs in /usr/share/seabios/ (I'm not exactly sure how qemu deals with those), and the path is different for other distros and other qemu binaries. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW