From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark H Weaver Subject: bug#27636: /dev/kvm went missing on i686, Linux 4.12 Date: Tue, 18 Jul 2017 16:02:06 -0400 Message-ID: <878tjlzf7l.fsf@netris.org> References: <87y3rwetng.fsf@elephly.net> <87fue4gpzl.fsf@netris.org> <878tjmhlqm.fsf@elephly.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:49349) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dXYi3-0005jA-KH for bug-guix@gnu.org; Tue, 18 Jul 2017 16:03:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dXYhy-0004Ao-Np for bug-guix@gnu.org; Tue, 18 Jul 2017 16:03:07 -0400 Received: from debbugs.gnu.org ([208.118.235.43]:44271) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1dXYhy-0004Aj-Ki for bug-guix@gnu.org; Tue, 18 Jul 2017 16:03:02 -0400 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1dXYhy-0006w4-6E for bug-guix@gnu.org; Tue, 18 Jul 2017 16:03:02 -0400 Sender: "Debbugs-submit" Resent-Message-ID: In-Reply-To: <878tjmhlqm.fsf@elephly.net> (Ricardo Wurmus's message of "Mon, 17 Jul 2017 22:06:09 +0200") List-Id: Bug reports for GNU Guix List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-guix-bounces+gcggb-bug-guix=m.gmane.org@gnu.org Sender: "bug-Guix" To: Ricardo Wurmus Cc: 27636@debbugs.gnu.org Ricardo Wurmus writes: > Mark H Weaver writes: > >> Ricardo Wurmus writes: >> >>> Since the update to Linux 4.12 my i686 machine no longer has /dev/kvm. >>> I ran =E2=80=9Cmodprobe kvm=E2=80=9D successfully, and =E2=80=9Clsmod= =E2=80=9D shows =E2=80=9Ckvm=E2=80=9D, but the >>> device node does not exist. >>> >>> Running =E2=80=9Cmodprobe kvm-intel=E2=80=9D prints: >>> >>> modprobe: ERROR: could not insert 'kvm_intel': Input/output error >> >> Does the kernel message buffer mention anything about "kvm" or "KVM"? >> >> dmesg | grep -i kvm > > No, there is no mention of =E2=80=9Ckvm=E2=80=9D or =E2=80=9CKVM=E2=80=9D= in the kernel messages. When you looked for "kvm" or "KVM", did your kernel message buffer still include the initial boot messages? The kernel message buffer is of a fixed size, so eventually the early messages are lost. The reason I ask is because I did some web searches looking for other people with the same problem, and what I found was that there was typically a kernel message at boot time explaining why KVM was disabled. In my case, on my Thinkpad X200 (which I'm sorry to say is running a proprietary BIOS for now, because I had to replace the motherboard recently and haven't yet gotten around to buying the needed clip to reflash) I see the message "kvm: disabled by bios". I'm fairly sure that I've seen /dev/kvm on this machine in the past. It might be that in earlier versions of Linux, /dev/kvm was created even when it couldn't be used, and now it's created only conditionally, but that's only a guess. I haven't made any changes to the kernel configuration except to add support for new modules and features as they become available, and as far as I can see, the relevant KVM options are enabled just as they have been in the past. If all else fails, you could try using the 4.9 or 4.4 kernel and see if that makes any difference. Mark