From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42247) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1co2uN-0003jo-Fz for qemu-devel@nongnu.org; Wed, 15 Mar 2017 02:59:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1co2uK-0002Ey-9W for qemu-devel@nongnu.org; Wed, 15 Mar 2017 02:59:43 -0400 Received: from mail-db5eur01on0099.outbound.protection.outlook.com ([104.47.2.99]:57632 helo=EUR01-DB5-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1co2uJ-0002Ee-K9 for qemu-devel@nongnu.org; Wed, 15 Mar 2017 02:59:40 -0400 Message-ID: <1489561105.24841.25.camel@nokia.com> From: Janne Huttunen Date: Wed, 15 Mar 2017 08:58:25 +0200 In-Reply-To: <1489510640.8844.18.camel@redhat.com> References: <1489510640.8844.18.camel@redhat.com> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC][PATCH 0/6] "bootonceindex" property List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: qemu-devel@nongnu.org > > =C2=A0 - Does this approach make sense? Any better ideas? > =C2=A0 > What is the use case? The short answer: emulating real hardware. Since real HW has this capability, there exist certain auxiliary systems that are built on it. Having similar semantics available in QEMU allows me to build a virtual machine that works with these systems without modifying them in any way. Also, the support I'm after already almost was in QEMU ('-boot once=3D'). It just didn't quite provide the functionality I wanted i.e. the 'bootindex' like operation. This patch series tries to bridge that gap. But hey, I wasn't sure if this was useful for other people too, and that's why the RFC. In principle I agree with you that in some specific cases QEMU has other means of doing things that necessarily don't exist in real HW. Obviously systems that are built for real HW don't use any such QEMU specific methods. Again, in some specific cases it might be possible to get close enough semantics without real "boot once" support and in others it probably won't be. Note that part of the semantics I'm after is that the "boot once" order can be set while the system is up and running. It may or may not be strictly necessary depending on the specific use case, but that's the way the real HW works.