From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42227) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gOkLV-0002Ex-El for qemu-devel@nongnu.org; Mon, 19 Nov 2018 09:16:16 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gOkLT-0005qa-Oa for qemu-devel@nongnu.org; Mon, 19 Nov 2018 09:16:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45642) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gOkLT-0005q6-JC for qemu-devel@nongnu.org; Mon, 19 Nov 2018 09:16:11 -0500 Date: Mon, 19 Nov 2018 14:16:07 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20181119141606.GC2365@work-vm> References: <20181119104330.GA2367@work-vm> <16966.1542632079@dschgrazlin2.units.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16966.1542632079@dschgrazlin2.units.it> Subject: Re: [Qemu-devel] 3.1.0-rc{0,1} doesn't start List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: balducci@units.it Cc: qemu-devel@nongnu.org * balducci@units.it (balducci@units.it) wrote: > hi > > thanks for taking the time to reply > > Dr. David Alan Gilbert writes: > > > I suspect that this might be some problem on my side, as I couldn't > > > find any similar report (apart some old (qemu-2.8.50) threads, that > > > didn't help) > > > > Not necessarily; can you tell me: > > a) At what point does it fail - immediately when booting the guest? > > Some time during the boot? Later? > > b) What guest does it happen on? > > a) the error happens almost immediately; I mean: when I run qemu from an > xterm, it doesn't even popup its window: it just dumps the error > message to the terminal and stops > b) the guest is an old windows XP OS; but, as I say above, all goes as > if qemu doesn't even load the OS image (at least this is my > impression) Thanks. > Meantime, I have tried to (quick&dirty) disable the error > catching/asserting in i386/kvm.c: > > install:41> diff ./qemu-3.1.0-rc1/target/i386/kvm.c.MSR_HACK ./qemu-3.1.0-rc1/target/i386/kvm.c > 2205c2205 > < if (ret < cpu->kvm_msr_buf->nmsrs) { > --- > > if (1==0) { > 2211c2211 > < assert(ret == cpu->kvm_msr_buf->nmsrs); > --- > > assert(1==1); > 2524c2524 > < if (ret < cpu->kvm_msr_buf->nmsrs) { > --- > > if (1==0) { > 2530c2530 > < assert(ret == cpu->kvm_msr_buf->nmsrs); > --- > > assert(1==1); > > and that makes qemu start and work without apparent problems. > Of course, that is a crude and risky (I guess) workaround... Yes, the gotcha is that the call writes a whole bunch of MSRs and when one fails all the ones after it don't get written either; so you get lots of weird problems due to whichever other MSRs are wrong. Dave > thanks again > > ciao > -gabriele -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK