On 9/11/2020 1:59 PM, Dr. David Alan Gilbert wrote:
> * Steven Sistare (steven.sist...@oracle.com) wrote:
>> On 7/30/2020 1:03 PM, Alex Bennée wrote:
>>>
>>> Steve Sistare <steven.sist...@oracle.com> 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.
>
> You might try the '--preconfig' option - that's pretty early on.
> The other one is adding a chardev and telling it to wait for a server;
> that'll wait until you telnet to the port.
>
> (Either way, this patch shouldn't really be part of this series, it's a
> separate discussion)
Sure, I will pull it from the series.
- Steve
>> - Steve
>>>> Usage:
>>>> qemu -pause <seconds>
>>>> or
>>>> export QEMU_PAUSE=<seconds>
>>>>
>>>> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
>>>> ---
>>>> 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;
>>>
>>>
>>
