Re: [PATCH 33/47] system/vl: add new option -target

[Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>]

On 8/31/2026 5:39 AM, Yonggang Luo wrote:
> I would suggest to handle the condition and argv0 and target name
> consitencely, here is my patch summary:
> - Parse -target with QEMU_OPTION_nouserconfig, right after
>   MODULE_INIT_TARGET_INFO, because later init depends on TargetInfo.
> - target_info_qom_set_target() takes Error **errp. A name comes from
>   -target or from argv0 (qemu-system-aarch64).
> - Define SYS_EMU_TARGET_UNSPECIFIED as SYS_EMU_TARGET__MAX. Bare
>   qemu-system with no suffix and no -target binds a dummy TargetInfo.
>   qemu-system-* still selects from the argv[0] suffix.
> - -M help lists the union. Starting a real board without a target
>   errors; -M none is allowed.
> - qemu_arch_available() is true when unspecified. query-target errors
>   instead of emitting an invalid SysEmuTarget.
> - Fuzz passes TARGET_NAME instead of relying on a unique TargetInfo.
> 
> and patch is attached to replace this commit and next commit
>

For now, I'll focus the efforts on the filtering mechanism for this
series. Once we agree, we can debate the details of single-binary itself.

> 
> 
> On Sat, Aug 29, 2026 at 7:04 AM Pierrick Bouvier
> <pierrick.bouvier@oss.qualcomm.com
> <mailto:pierrick.bouvier@oss.qualcomm.com>> wrote:
>>
>> This commit adds a new option -target, which can be allowed to set
>> current target, or retrieve list of targets available with 'help'.
>>
>> This option is the first we need to handle, as all the rest of
>> initialization depends on it.
>>
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com
> <mailto:pierrick.bouvier@oss.qualcomm.com>>
>> ---
>>  include/qemu/target-info-qom.h |  1 +
>>  qemu-options.hx                |  8 ++++++++
>>  system/vl.c                    | 34 +++++++++++++++++++++++++++++++++-
>>  target-info-qom.c              | 33 ++++++++++++++++++++++++++++++++-
>>  4 files changed, 74 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/qemu/target-info-qom.h b/include/qemu/target-
> info-qom.h
>> index 91be415ed33..87f3a51ccd4 100644
>> --- a/include/qemu/target-info-qom.h
>> +++ b/include/qemu/target-info-qom.h
>> @@ -26,5 +26,6 @@ typedef struct TargetInfoQomClass {
>>  OBJECT_DECLARE_TYPE(TargetInfoQom, TargetInfoQomClass, TARGET_INFO)
>>
>>  void target_info_qom_set_target(void);
>> +void target_info_qom_set_target_from_name(const char *name);
>>
>>  #endif /* QEMU_TARGET_INFO_QOM_H */
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 562c4c2b035..68d0c1d42da 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -24,6 +24,14 @@ SRST
>>      Display version information and exit
>>  ERST
>>
>> +DEF("target", HAS_ARG, QEMU_OPTION_target, \
>> +    "-target target  selects the target architecture ('-target help'
> for list)\n",
>> +    QEMU_ARCH_ALL)
>> +SRST
>> +``-target target``
>> +    Selects target architecture ('-target help' for list)
>> +ERST
>> +
>>  DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
>>      "-machine [type=]name[,prop=value[,...]]\n"
>>      "                selects emulated machine ('-machine help' for
> list)\n"
>> diff --git a/system/vl.c b/system/vl.c
>> index f7f8aabd122..60c5ce85580 100644
>> --- a/system/vl.c
>> +++ b/system/vl.c
>> @@ -281,6 +281,15 @@ static QemuOptsList qemu_accel_opts = {
>>      },
>>  };
>>
>> +static QemuOptsList qemu_target_opts = {
>> +    .name = "target",
>> +    .implied_opt_name = "target",
>> +    .head = QTAILQ_HEAD_INITIALIZER(qemu_target_opts.head),
>> +    .desc = {
>> +        { /* end of list */ },
>> +    },
>> +};
>> +
>>  static QemuOptsList qemu_boot_opts = {
>>      .name = "boot-opts",
>>      .implied_opt_name = "order",
>> @@ -2891,6 +2900,7 @@ void qemu_init(int argc, char **argv)
>>      qemu_add_opts(&qemu_semihosting_config_opts);
>>      qemu_add_opts(&qemu_fw_cfg_opts);
>>      qemu_add_opts(&qemu_action_opts);
>> +    qemu_add_opts(&qemu_target_opts);
>>      qemu_add_run_with_opts();
>>      module_call_init(MODULE_INIT_OPTS);
>>
>> @@ -2900,7 +2910,26 @@ void qemu_init(int argc, char **argv)
>>      os_setup_limits();
>>
>>      module_call_init(MODULE_INIT_TARGET_INFO);
>> -    target_info_qom_set_target();
>> +
>> +    /*
>> +     * Identify target: first from option, then from argv[0].
>> +     * This happens even before handling --help option, because it
> may contain
>> +     * entries that are target specific.
>> +     */
>> +    for (int idx = 1; idx < argc;) {
>> +        if (argv[idx][0] != '-') {
>> +            idx++;
>> +        } else {
>> +            const QEMUOption *popt = lookup_opt(argc, argv, &optarg,
> &idx);
>> +            if (popt->index == QEMU_OPTION_target) {
>> +                target_info_qom_set_target_from_name(optarg);
>> +                break;
>> +            }
>> +        }
>> +    }
>> +    if (!target_info()) {
>> +        target_info_qom_set_target();
>> +    }
>>
>>      module_init_info(qemu_modinfo);
>>      module_allow_arch(target_name());
>> @@ -2948,6 +2977,9 @@ void qemu_init(int argc, char **argv)
>>                  exit(1);
>>              }
>>              switch(popt->index) {
>> +            case QEMU_OPTION_target:
>> +                /* handled previously, ignore it here */
>> +                break;
>>              case QEMU_OPTION_cpu:
>>                  /* hw initialization will check this */
>>                  cpu_option = optarg;
>> diff --git a/target-info-qom.c b/target-info-qom.c
>> index 6965e4d1169..a2f506c15ef 100644
>> --- a/target-info-qom.c
>> +++ b/target-info-qom.c
>> @@ -9,6 +9,7 @@
>>  #include "qemu/osdep.h"
>>  #include "qapi/error.h"
>>  #include "qom/object.h"
>> +#include "qemu/error-report.h"
>>  #include "qemu/target-info-impl.h"
>>  #include "qemu/target-info-init.h"
>>  #include "qemu/target-info-qom.h"
>> @@ -50,6 +51,36 @@ void target_info_qom_set_target(void)
>>                                   "no target-info is available" :
>>                                   "more than one target-info is
> available");
>>      }
>> -
>>      target_info_ptr = TARGET_INFO_CLASS(targets->data)->target_info;
>>  }
>> +
>> +static void list_targets_available(void)
>> +{
>> +    printf("List of targets available:\n");
>> +    g_autoptr(GSList) targets =
> object_class_get_list_sorted(TYPE_TARGET_INFO, false);
>> +    for (GSList *elem = targets; elem; elem = elem->next) {
>> +        const TargetInfo *ti = TARGET_INFO_CLASS(elem->data)-
>>target_info;
>> +        printf("- %s\n", ti->target_name);
>> +    }
>> +}
>> +
>> +void target_info_qom_set_target_from_name(const char *name)
>> +{
>> +    if (!strcmp(name, "help")) {
>> +        list_targets_available();
>> +        exit(0);
>> +    }
>> +
>> +    g_autoptr(GSList) targets =
> object_class_get_list(TYPE_TARGET_INFO, false);
>> +    for (GSList *elem = targets; elem; elem = elem->next) {
>> +        const TargetInfo *ti = TARGET_INFO_CLASS(elem->data)-
>>target_info;
>> +        if (!strcmp(name, ti->target_name)) {
>> +            target_info_ptr = ti;
>> +            return;
>> +        }
>> +    }
>> +
>> +    error_report("target '%s' is not available", name);
>> +    list_targets_available();
>> +    exit(1);
>> +}
>> --
>> 2.43.0
>>
>>
> 
> 
> --
>          此致
> 礼
> 罗勇刚
> Yours
>     sincerely,
> Yonggang Luo