From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60557) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dYA6P-0006rW-TA for qemu-devel@nongnu.org; Thu, 20 Jul 2017 07:58:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dYA6L-0006Ly-Vv for qemu-devel@nongnu.org; Thu, 20 Jul 2017 07:58:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34578) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dYA6L-0006Ln-N9 for qemu-devel@nongnu.org; Thu, 20 Jul 2017 07:58:41 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B917313A60 for ; Thu, 20 Jul 2017 11:58:39 +0000 (UTC) From: Markus Armbruster References: <20170720091902.22476-1-apahim@redhat.com> <20170720091902.22476-3-apahim@redhat.com> Date: Thu, 20 Jul 2017 13:58:33 +0200 In-Reply-To: <20170720091902.22476-3-apahim@redhat.com> (Amador Pahim's message of "Thu, 20 Jul 2017 11:19:01 +0200") Message-ID: <87d18v1frq.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v3 2/3] qemu.py: include debug information on launch error List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Amador Pahim Cc: qemu-devel@nongnu.org, kwolf@redhat.com, ldoktor@redhat.com, ehabkost@redhat.com, mreitz@redhat.com, crosa@redhat.com, famz@redhat.com Amador Pahim writes: > When launching a VM, if an exception happens and the VM is not > initiated, it is useful to see the qemu command line that was executed > and the output of that command. > > Before the patch: > > >>> VM = qemu.QEMUMachine('../aarch64-softmmu/qemu-system-aarch64') > >>> VM.launch() > Traceback (most recent call last): > File "", line 1, in > File "qemu.py", line 137, in launch > self._post_launch() > File "qemu.py", line 121, in _post_launch > self._qmp.accept() > File "qmp/qmp.py", line 145, in accept > self.__sock, _ = self.__sock.accept() > File "/usr/lib64/python2.7/socket.py", line 206, in accept > sock, addr = self._sock.accept() > socket.timeout: timed out > > After the patch: > > >>> VM = qemu.QEMUMachine('../aarch64-softmmu/qemu-system-aarch64') > >>> VM.launch() > Traceback (most recent call last): > File "", line 1, in > File "qemu.py", line 156, in launch > raise RuntimeError(msg) > RuntimeError: Error launching VM. > Original Exception: > Traceback (most recent call last): > File "qemu.py", line 138, in launch > self._post_launch() > File "qemu.py", line 122, in _post_launch > self._qmp.accept() > File "qmp/qmp.py", line 145, in accept > self.__sock, _ = self.__sock.accept() > File "/usr/lib64/python2.7/socket.py", line 206, in accept > sock, addr = self._sock.accept() > timeout: timed out > Command: > /usr/bin/qemu-system-aarch64 -chardev socket,id=mon, > path=/var/tmp/qemu-23958-monitor.sock -mon chardev=mon,mode=control > -display none -vga none > Output: > qemu-system-aarch64: No machine specified, and there is no default > Use -machine help to list supported machines > > Also, if the launch() faces an exception, the 'except' now will use args > to fill the debug information. So this patch assigns 'args' earlier, > assuring it will be available for the 'except'. > > Signed-off-by: Amador Pahim > Reviewed-by: Fam Zheng > --- > scripts/qemu.py | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/scripts/qemu.py b/scripts/qemu.py > index f0fade32bd..2707ae7f75 100644 > --- a/scripts/qemu.py > +++ b/scripts/qemu.py > @@ -18,6 +18,7 @@ import os > import sys > import subprocess > import qmp.qmp > +import traceback > > > class QEMUMachine(object): > @@ -129,17 +130,30 @@ class QEMUMachine(object): > '''Launch the VM and establish a QMP connection''' > devnull = open('/dev/null', 'rb') > qemulog = open(self._qemu_log_path, 'wb') > + args = self._wrapper + [self._binary] + self._base_args() + self.args > try: > self._pre_launch() > - args = self._wrapper + [self._binary] + self._base_args() + self._args > self._popen = subprocess.Popen(args, stdin=devnull, stdout=qemulog, > stderr=subprocess.STDOUT, shell=False) > self._post_launch() Lifting the assignment out of the try makes sense, because exceptions there are programming errors. Why are ._pre_launch() and ._post_launch() inside the try? > except: Why do we catch all exceptions, and not just subprocess.CalledProcessError? > + self._load_io_log() > if self.is_running(): I suspect we can't get here only for "odd" exceptions, not for subprocess.CalledProcessError. > self._popen.kill() > self._popen.wait() > - self._load_io_log() > + else: > + exc_type, exc_value, exc_traceback = sys.exc_info() > + msg = ('Error launching VM.\n' > + 'Original Exception: \n%s' > + 'Command:\n%s\n' > + 'Output:\n%s\n' % > + (''.join(traceback.format_exception(exc_type, > + exc_value, > + exc_traceback)), > + ' '.join(args), > + self._iolog)) > + self._post_shutdown() > + raise RuntimeError(msg) > self._post_shutdown() > raise Why do we print a traceback when subprocess.CalledProcessError?