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.
- 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;
>
>
