From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59292) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ckr7R-0007P2-M9 for qemu-devel@nongnu.org; Mon, 06 Mar 2017 06:48:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ckr7N-0005zp-Hj for qemu-devel@nongnu.org; Mon, 06 Mar 2017 06:48:01 -0500 Date: Mon, 6 Mar 2017 08:47:52 -0300 From: Eduardo Habkost Message-ID: <20170306114752.GS2778@thinpad.lan.raisama.net> References: <1485868319-16151-1-git-send-email-thuth@redhat.com> <1485868319-16151-3-git-send-email-thuth@redhat.com> <20170303145807.GC11509@thinpad.lan.raisama.net> <20170305230627.GA12030@umbus.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170305230627.GA12030@umbus.fritz.box> Subject: Re: [Qemu-devel] [PATCH 2/2] vl: Print CPU help after we've registered the CPU accelerators List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: Thomas Huth , qemu-ppc@nongnu.org, Paolo Bonzini , Bharata B Rao , qemu-devel@nongnu.org, Alexander Graf , Markus Armbruster On Mon, Mar 06, 2017 at 10:06:27AM +1100, David Gibson wrote: > On Fri, Mar 03, 2017 at 11:58:07AM -0300, Eduardo Habkost wrote: > > On Tue, Jan 31, 2017 at 02:11:59PM +0100, Thomas Huth wrote: > > > When running with KVM on POWER, we register some CPU types during > > > the initialization function of the ppc64 KVM code (which unfortunately > > > also can not be done via a type_init() like it is done on x86). > > > > Can you elaborate why it can't be done via type_init()? If the > > QOM type hierarchy depends on any runtime data unavailable at > > type_init(), we should fix that. > > Hmm.. how? This is specifically for the special 'host' cpu in the > case of KVM. We can't use a static configuration here, because there > are things on the host that could limit what features of the CPU are > available for guest use. So, we need KVM to be initialized in order > to query that information. There's nothing saying you need to query that information before type_register() or during class_init, does it? The behavior of TYPE_HOST_POWERPC_CPU after object_new() is called can be as dynamic as you want it to, but the QOM type hierarchy is supposed to be static. Registering QOM types outside type_init() is only causing us problems and we should stop doing that. > > > > So to > > > be able to see these updates in the CPU help text, the code that calls > > > list_cpus() has to be run after configure_accelerator(). This move should > > > be fine since the "cpu_model" variable is also never used before the call > > > to configure_accelerator(), and thus there should not be any unwanted > > > side effects in the code before configure_accelerator() if the user > > > started QEMU with "-cpu ?" or "-cpu help". > > > > > > Signed-off-by: Thomas Huth > > > > I am not convinced that the output of "-cpu help" and > > "-cpu help -machine accel=kvm" should look different. Do you have > > an example of what exactly is wrong with the output currently? > > > > I actually believe list_cpus() needs to be called _earlier_, not > > later. Otherwise we won't be able to fix this bug: > > > > $ qemu-system-arm -cpu help > > qemu-system-arm:/usr/local/etc/qemu/qemu.conf:1: No machine specified, and there is no default > > Use -machine help to list supported machines > > $ > > > > > --- > > > vl.c | 10 +++++----- > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/vl.c b/vl.c > > > index 0b72b12..315c5c3 100644 > > > --- a/vl.c > > > +++ b/vl.c > > > @@ -4055,11 +4055,6 @@ int main(int argc, char **argv, char **envp) > > > qemu_set_hw_version(machine_class->hw_version); > > > } > > > > > > - if (cpu_model && is_help_option(cpu_model)) { > > > - list_cpus(stdout, &fprintf, cpu_model); > > > - exit(0); > > > - } > > > - > > > if (!trace_init_backends()) { > > > exit(1); > > > } > > > @@ -4298,6 +4293,11 @@ int main(int argc, char **argv, char **envp) > > > > > > configure_accelerator(current_machine); > > > > > > + if (cpu_model && is_help_option(cpu_model)) { > > > + list_cpus(stdout, &fprintf, cpu_model); > > > + exit(0); > > > + } > > > + > > > if (qtest_chrdev) { > > > qtest_init(qtest_chrdev, qtest_log, &error_fatal); > > > } > > > > -- > David Gibson | I'll have my music baroque, and my code > david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ > | _way_ _around_! > http://www.ozlabs.org/~dgibson -- Eduardo