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Date:   Mon, 1 Jul 2019 10:14:03 -0400
From:   Joel Fernandes <joel@joelfernandes.org>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     linux-kernel@vger.kernel.org,
        Josh Triplett <josh@joshtriplett.org>, kernel-team@android.com,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        linux-kselftest@vger.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        "Paul E. McKenney" <paulmck@linux.ibm.com>, rcu@vger.kernel.org,
        Shuah Khan <shuah@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>, dvyukov@google.com
Subject: Re: [RFC 3/3] Revert "rcutorture: Tweak kvm options"
Message-ID: <20190701141403.GA246562@google.com>
References: <20190701040415.219001-1-joel@joelfernandes.org>
 <20190701040415.219001-3-joel@joelfernandes.org>
 <20190701122358.nzebpuunp6o5jxhx@linutronix.de>
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On Mon, Jul 01, 2019 at 02:23:58PM +0200, Sebastian Andrzej Siewior wrote:
> On 2019-07-01 00:04:15 [-0400], Joel Fernandes (Google) wrote:
> > This reverts commit a6fda6dab93c2c06ef4b8cb4b9258df6674d2438 which
> > causes kvm.sh to not run on my machines. The qemu-system-x86_64 command
> > runs but does nothing.
> 
> Nope. I would like to know *why* you need 'noapic' to work. Is it a
> brand new or old qemu-system-x86_64?

I did not have time to debug yesterday and I posted this particular revert as
an 'RFC' just to make aware of this problem.

I spent some more time just now, it looks like this has nothing to do with
'noapic' and appears to be a problem on debian distros with the e1000e NIC.
May be this NIC was added to the virtual hardware because of -machine in the
patch?

Any if I add the following to the qemu command that kvm.sh runs, it works again:
-net nic,model=e1000

Without it I get:
 qemu-system-x86_64: Initialization of device e1000e failed: failed to find romfile "efi-e1000e.rom"

Seems to be mentioned here:
https://bugs.launchpad.net/ubuntu/+source/ipxe/+bug/1737211

And in syzkaller as well:
https://github.com/google/syzkaller/blob/master/vm/qemu/qemu.go#L88

Adding Dmitry who is syzkaller owner for any thoughts as well.

I'm happy to write a patch to set the nic model as e1000 and send it out if
we agree this solution is good enough.

 - Joel