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Thu, 30 Jul 2020 18:14:08 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 06UIE7CE006747; Thu, 30 Jul 2020 18:14:07 GMT Received: from [10.39.200.60] (/10.39.200.60) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 30 Jul 2020 11:14:06 -0700 Subject: Re: [PATCH V1 12/32] vl: pause option To: =?UTF-8?Q?Alex_Benn=c3=a9e?= References: <1596122076-341293-1-git-send-email-steven.sistare@oracle.com> <1596122076-341293-13-git-send-email-steven.sistare@oracle.com> <87r1stdjes.fsf@linaro.org> From: Steven Sistare Organization: Oracle Corporation Message-ID: Date: Thu, 30 Jul 2020 14:14:03 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <87r1stdjes.fsf@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9698 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 mlxlogscore=999 mlxscore=0 suspectscore=0 bulkscore=0 malwarescore=0 spamscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007300129 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9698 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 clxscore=1015 mlxlogscore=999 malwarescore=0 impostorscore=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007300129 Received-SPF: pass client-ip=156.151.31.85; envelope-from=steven.sistare@oracle.com; helo=userp2120.oracle.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/30 13:52:52 X-ACL-Warn: Detected OS = Linux 3.1-3.10 [fuzzy] X-Spam_score_int: -53 X-Spam_score: -5.4 X-Spam_bar: ----- X-Spam_report: (-5.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Daniel P. Berrange" , "Michael S. Tsirkin" , Markus Armbruster , Juan Quintela , "Dr. David Alan Gilbert" , qemu-devel@nongnu.org, Alex Williamson , Stefan Hajnoczi , =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , Paolo Bonzini , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 7/30/2020 1:03 PM, Alex Bennée wrote: > > Steve Sistare writes: > >> Provide the -pause command-line parameter and the QEMU_PAUSE environment >> variable to briefly pause QEMU in main and allow a developer to attach gdb. >> Useful when the developer does not invoke QEMU directly, such as when using >> libvirt. > > How does this differ from -S? The -S flag runs qemu to the main loop but does not start the guest. Lots of code that you may need to debug runs before you get there. - Steve >> Usage: >> qemu -pause >> or >> export QEMU_PAUSE= >> >> Signed-off-by: Steve Sistare >> --- >> qemu-options.hx | 9 +++++++++ >> softmmu/vl.c | 15 ++++++++++++++- >> 2 files changed, 23 insertions(+), 1 deletion(-) >> >> diff --git a/qemu-options.hx b/qemu-options.hx >> index 708583b..8505cf2 100644 >> --- a/qemu-options.hx >> +++ b/qemu-options.hx >> @@ -3668,6 +3668,15 @@ SRST >> option is experimental. >> ERST >> >> +DEF("pause", HAS_ARG, QEMU_OPTION_pause, \ >> + "-pause secs Pause for secs seconds on entry to main.\n", QEMU_ARCH_ALL) >> + >> +SRST >> +``--pause secs`` >> + Pause for a number of seconds on entry to main. Useful for attaching >> + a debugger after QEMU has been launched by some other entity. >> +ERST >> + > > It seems like having an option to race with the debugger is just asking > for trouble. > >> DEF("S", 0, QEMU_OPTION_S, \ >> "-S freeze CPU at startup (use 'c' to start execution)\n", >> QEMU_ARCH_ALL) >> diff --git a/softmmu/vl.c b/softmmu/vl.c >> index 8478778..951994f 100644 >> --- a/softmmu/vl.c >> +++ b/softmmu/vl.c >> @@ -2844,7 +2844,7 @@ static void create_default_memdev(MachineState *ms, const char *path) >> >> void qemu_init(int argc, char **argv, char **envp) >> { >> - int i; >> + int i, seconds; >> int snapshot, linux_boot; >> const char *initrd_filename; >> const char *kernel_filename, *kernel_cmdline; >> @@ -2882,6 +2882,13 @@ void qemu_init(int argc, char **argv, char **envp) >> QemuPluginList plugin_list = QTAILQ_HEAD_INITIALIZER(plugin_list); >> int mem_prealloc = 0; /* force preallocation of physical target memory */ >> >> + if (getenv("QEMU_PAUSE")) { >> + seconds = atoi(getenv("QEMU_PAUSE")); >> + printf("Pausing %d seconds for debugger. QEMU PID is %d\n", >> + seconds, getpid()); >> + sleep(seconds); >> + } >> + >> os_set_line_buffering(); >> >> error_init(argv[0]); >> @@ -3204,6 +3211,12 @@ void qemu_init(int argc, char **argv, char **envp) >> case QEMU_OPTION_gdb: >> add_device_config(DEV_GDB, optarg); >> break; >> + case QEMU_OPTION_pause: >> + seconds = atoi(optarg); >> + printf("Pausing %d seconds for debugger. QEMU PID is %d\n", >> + seconds, getpid()); >> + sleep(seconds); >> + break; >> case QEMU_OPTION_L: >> if (is_help_option(optarg)) { >> list_data_dirs = true; > >