From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Bareiro Subject: Re: kvm-88: KVM_APIC_READ: read reserved register b0 Date: Sun, 30 Aug 2009 12:28:47 -0300 Message-ID: <20090830152847.GC3014@defiant.freesoftware.org> References: <4A97AB92.9090509@l-mx.de> <20090829212036.GA3014@defiant.freesoftware.org> <4A9A4D7F.3010904@l-mx.de> <20090830100159.GT30093@redhat.com> <4A9A6596.3010302@l-mx.de> <20090830114959.GV30093@redhat.com> Reply-To: dbareiro@gmx.net Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="eRtJSFbw+EEWtPj3" To: kvm@vger.kernel.org Return-path: Received: from mail.gmx.net ([213.165.64.20]:44991 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752935AbZH3P2v (ORCPT ); Sun, 30 Aug 2009 11:28:51 -0400 Received: from defiant (defiant.freesoftware.org [10.1.0.65]) by hermes.freesoftware.org (Postfix) with ESMTP id D2941620 for ; Sun, 30 Aug 2009 12:28:14 -0300 (ART) Content-Disposition: inline In-Reply-To: <20090830114959.GV30093@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: --eRtJSFbw+EEWtPj3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sunday, 30 August 2009 14:49:59 +0300, Gleb Natapov wrote: > > > This printk no longer exists in upstream kvm. Between emails of the list, I found the suggestion to apply this [1] patch, but I suppose that not yet it must be applied in the download version. > > just to be curious: What was the reason to add that debugging > > message? > Because well behaved OS shouldn't read write only register. > Unfortunately older Linux kernels sometimes uses xchg to access > eoi(b0) apic register which will generate read/write. According to I see, guest kernel is 2.6.26-2-486. Apparently, after a reboot, the OS boots with it instead of amd64 kernel. After boot with amd64 kernel, no longer flooding in syslog takes place. I didn't test yet, but I think that with a 686 kernel also the problem had been solved from the moment that the kernel is nearer the hardware architecture which I'm using. Thanks to both for your replies. Regards, Daniel [1] http://thread.gmane.org/gmane.comp.emulators.qemu/24029 --=20 Fingerprint: BFB3 08D6 B4D1 31B2 72B9 29CE 6696 BF1B 14E6 1D37 Powered by Debian GNU/Linux Squeeze - Linux user #188.598 --eRtJSFbw+EEWtPj3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkqamq8ACgkQZpa/GxTmHTfsngCeIOmDG/9PH9/1Prtk5no19yao noUAn11UDONOZEf1OQK918B3uj9gLZQF =Wh0C -----END PGP SIGNATURE----- --eRtJSFbw+EEWtPj3--