From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NMOL5-0001Fd-5p for qemu-devel@nongnu.org; Sun, 20 Dec 2009 11:08:59 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NMOL0-0001E0-6T for qemu-devel@nongnu.org; Sun, 20 Dec 2009 11:08:58 -0500 Received: from [199.232.76.173] (port=44011 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NMOKz-0001Dv-Sn for qemu-devel@nongnu.org; Sun, 20 Dec 2009 11:08:53 -0500 Received: from mail-gx0-f223.google.com ([209.85.217.223]:55362) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NMOKz-0006bd-IL for qemu-devel@nongnu.org; Sun, 20 Dec 2009 11:08:53 -0500 Received: by gxk23 with SMTP id 23so4761476gxk.2 for ; Sun, 20 Dec 2009 08:08:52 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20091220155201.GP4490@redhat.com> References: <20091220083857.GE4490@redhat.com> <20091220145200.GA6706@redhat.com> <4B2E3BA0.7080004@codemonkey.ws> <20091220150751.GL4490@redhat.com> <4B2E3E96.7090708@codemonkey.ws> <20091220152346.GM4490@redhat.com> <4B2E42A2.6030600@codemonkey.ws> <20091220153347.GN4490@redhat.com> <4B2E453A.3060004@codemonkey.ws> <20091220155201.GP4490@redhat.com> From: Blue Swirl Date: Sun, 20 Dec 2009 16:08:32 +0000 Message-ID: Subject: Re: [Qemu-devel] Re: [SeaBIOS] [PATCH 0/8] option rom loading overhaul. Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: Gerd Hoffmann , qemu-devel@nongnu.org On Sun, Dec 20, 2009 at 3:52 PM, Gleb Natapov wrote: > On Sun, Dec 20, 2009 at 09:39:38AM -0600, Anthony Liguori wrote: >> Gleb Natapov wrote: >> >>More importantly though, what's the use-case here? >> >> >> >Use-case for what? This just what need to be done for correct HW >> >emulation. >> >> Live migration is transparent to the guest. =C2=A0The fact that firmware >> can upgrade itself without the guest doing anything is not something >> that really has a real world equivalent. >> >> Even if it did, whether that automatic upgrade happens after a >> reboot vs. a hard power cycle is irrelevant. =C2=A0The guest has no >> knowledge of the fact that the automatic firmware upgrade happened >> so if it gets delayed indefinitely, it doesn't matter. >> >> It's not a matter of correctness IMHO. >> > Ah now I see what you mean. New FW has to be used after reboot because ol= d > one may not be able to init HW any longer. Suppose some bug in cirrus > emulation has being fixed and old vga bios should be accommodated to > those changes, if old vga bios will run after reset video output may not > work. Thinking about it we'll have the same problem if migration happens > during vga bios loading, but this is MUCH less likely to happen. > >> I can understand an argument for predictability wrt wanted to be >> able to guarantee that after the first reboot during a live >> migration, you'll get the new firmware. =C2=A0I'm not sure that's less >> predictable then hard shutdown/start-up and I'm not sure I can >> really make an argument for one way vs. the other. >> > system_reset _is_ hard shutdown/start-up. If it is not it is a bug, we > just arguing if the same applies for the case that migration was done > between boot and reset. Some devices are careful enough to implement warm reset using a flag, see for example hw/sun4u.c. If you want more precision, you could introduce for example system_off_on with the memory clearing behavior you want.