On 10/7/2026 2:42 PM, Yonggang Luo wrote: > On Thu, Oct 8, 2026 at 4:44 AM Pierrick Bouvier > <[email protected]> wrote: >> >> On 10/7/2026 4:48 AM, Yonggang Luo wrote: >>> Change TypeInfo.is_available to the new TypeIsAvailable type, which >>> takes a const TargetInfo *. Registration passes target_info(), so >>> behavior is unchanged. object.h only forward-declares TargetInfo. >>> >>> Switch the existing users (raspi, raspi4b, ast27x0 evb and fc) and the >>> generated machine parents to the matching target_is_<arch> helpers. >>> >>> Signed-off-by: Yonggang Luo <[email protected]> >>> --- >>> hw/arm/aspeed_ast27x0-fc.c | 2 +- >>> hw/arm/aspeed_ast27x0_evb.c | 4 ++-- >>> hw/arm/raspi.c | 4 ++-- >>> hw/arm/raspi4b.c | 2 +- >>> hw/arm/virt.c | 4 ++-- >>> hw/m68k/virt.c | 4 ++-- >>> hw/or1k/virt.c | 2 +- >>> include/qom/object.h | 12 +++++++++++- >>> qom/object.c | 3 ++- >>> 9 files changed, 24 insertions(+), 13 deletions(-) >>> >>> diff --git a/hw/arm/aspeed_ast27x0-fc.c b/hw/arm/aspeed_ast27x0-fc.c >>> index 73362b60d2a..8a7c6a116ac 100644 >>> --- a/hw/arm/aspeed_ast27x0-fc.c >>> +++ b/hw/arm/aspeed_ast27x0-fc.c >>> @@ -234,7 +234,7 @@ static const TypeInfo ast2700fc_types[] = { >>> .parent = TYPE_MACHINE, >>> .class_init = ast2700fc_class_init, >>> .instance_size = sizeof(Ast2700FCState), >>> - .is_available = target_aarch64, >>> + .is_available = target_is_aarch64, >>> }, >>> }; >>> >>> diff --git a/hw/arm/aspeed_ast27x0_evb.c b/hw/arm/aspeed_ast27x0_evb.c >>> index 460c9ff0d2e..02a8cff1d9d 100644 >>> --- a/hw/arm/aspeed_ast27x0_evb.c >>> +++ b/hw/arm/aspeed_ast27x0_evb.c >>> @@ -75,13 +75,13 @@ static const TypeInfo aspeed_ast27x0_evb_types[] = { >>> .name = MACHINE_TYPE_NAME("ast2700a1-evb"), >>> .parent = TYPE_ASPEED_MACHINE, >>> .class_init = aspeed_machine_ast2700a1_evb_class_init, >>> - .is_available = target_aarch64, >>> + .is_available = target_is_aarch64, >>> }, >>> { >>> .name = MACHINE_TYPE_NAME("ast2700a2-evb"), >>> .parent = TYPE_ASPEED_MACHINE, >>> .class_init = aspeed_machine_ast2700a2_evb_class_init, >>> - .is_available = target_aarch64, >>> + .is_available = target_is_aarch64, >>> } >>> }; >>> >>> diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c >>> index fadbacb2534..22b06c6ca22 100644 >>> --- a/hw/arm/raspi.c >>> +++ b/hw/arm/raspi.c >>> @@ -403,12 +403,12 @@ static const TypeInfo raspi_machine_types[] = { >>> .name = MACHINE_TYPE_NAME("raspi3ap"), >>> .parent = TYPE_RASPI_MACHINE, >>> .class_init = raspi3ap_machine_class_init, >>> - .is_available = target_aarch64, >>> + .is_available = target_is_aarch64, >>> }, { >>> .name = MACHINE_TYPE_NAME("raspi3b"), >>> .parent = TYPE_RASPI_MACHINE, >>> .class_init = raspi3b_machine_class_init, >>> - .is_available = target_aarch64, >>> + .is_available = target_is_aarch64, >>> }, { >>> .name = TYPE_RASPI_MACHINE, >>> .parent = TYPE_RASPI_BASE_MACHINE, >>> diff --git a/hw/arm/raspi4b.c b/hw/arm/raspi4b.c >>> index 566d64572db..a1dc477f25e 100644 >>> --- a/hw/arm/raspi4b.c >>> +++ b/hw/arm/raspi4b.c >>> @@ -121,7 +121,7 @@ static const TypeInfo raspi4b_machine_type = { >>> .parent = TYPE_RASPI_BASE_MACHINE, >>> .instance_size = sizeof(Raspi4bMachineState), >>> .class_init = raspi4b_machine_class_init, >>> - .is_available = target_aarch64, >>> + .is_available = target_is_aarch64, >>> }; >>> >>> static void raspi4b_machine_register_type(void) >>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c >>> index 9d192515d85..18160f7fad3 100644 >>> --- a/hw/arm/virt.c >>> +++ b/hw/arm/virt.c >>> @@ -132,7 +132,7 @@ static void arm_virt_compat_default_set(MachineClass >>> *mc) >>> .name = MACHINE_VER_TYPE_NAME("virt", __VA_ARGS__), \ >>> .parent = TYPE_VIRT_MACHINE, \ >>> .class_init = MACHINE_VER_SYM(class_init, virt, __VA_ARGS__), \ >>> - .is_available = target_base_arm, \ >>> + .is_available = target_is_base_arm, \ >>> }; \ >>> static void MACHINE_VER_SYM(register, virt, __VA_ARGS__)(void) \ >>> { \ >>> @@ -4430,7 +4430,7 @@ static const TypeInfo virt_machine_info = { >>> { TYPE_HOTPLUG_HANDLER }, >>> { } >>> }, >>> - .is_available = target_base_arm, >>> + .is_available = target_is_base_arm, >>> }; >>> >>> static void machvirt_machine_init(void) >>> diff --git a/hw/m68k/virt.c b/hw/m68k/virt.c >>> index e52546e4fab..ad2a43ef3fb 100644 >>> --- a/hw/m68k/virt.c >>> +++ b/hw/m68k/virt.c >>> @@ -327,7 +327,7 @@ static const TypeInfo virt_machine_info = { >>> .parent = TYPE_MACHINE, >>> .abstract = true, >>> .class_init = virt_machine_class_init, >>> - .is_available = target_m68k, >>> + .is_available = target_is_m68k, >>> }; >>> >>> static void virt_machine_register_types(void) >>> @@ -355,7 +355,7 @@ type_init(virt_machine_register_types) >>> .name = MACHINE_VER_TYPE_NAME("virt", __VA_ARGS__), \ >>> .parent = MACHINE_TYPE_NAME("virt"), \ >>> .class_init = MACHINE_VER_SYM(class_init, virt, __VA_ARGS__), \ >>> - .is_available = target_m68k, \ >>> + .is_available = target_is_m68k, \ >>> }; \ >>> static void MACHINE_VER_SYM(register, virt, __VA_ARGS__)(void) \ >>> { \ >>> diff --git a/hw/or1k/virt.c b/hw/or1k/virt.c >>> index a3ff903839b..89fb786641f 100644 >>> --- a/hw/or1k/virt.c >>> +++ b/hw/or1k/virt.c >>> @@ -559,7 +559,7 @@ static const TypeInfo or1ksim_machine_typeinfo = { >>> .parent = TYPE_MACHINE, >>> .class_init = openrisc_virt_machine_init, >>> .instance_size = sizeof(OR1KVirtState), >>> - .is_available = target_or1k, >>> + .is_available = target_is_or1k, >>> }; >>> >>> static void or1ksim_machine_init_register_types(void) >>> diff --git a/include/qom/object.h b/include/qom/object.h >>> index 4c0645817a5..7d52a15f6b8 100644 >>> --- a/include/qom/object.h >>> +++ b/include/qom/object.h >>> @@ -17,6 +17,7 @@ >>> #include "qapi/qapi-builtin-types.h" >>> #include "qemu/module.h" >>> >>> +typedef struct TargetInfo TargetInfo; >>> struct TypeImpl; >>> typedef struct TypeImpl *Type; >>> >>> @@ -117,6 +118,15 @@ typedef void (ObjectUnparent)(Object *obj); >>> */ >>> typedef void (ObjectFree)(void *obj); >>> >>> +/** >>> + * typedef TypeIsAvailable: >>> + * @ti: TargetInfo to test. >>> + * >>> + * Returns whether a type is available for @ti. Typical implementations >>> + * are target_is_*(). >>> + */ >>> +typedef bool (TypeIsAvailable)(const TargetInfo *ti); >>> + >>> #define OBJECT_CLASS_CAST_CACHE 4 >>> >>> /** >>> @@ -498,7 +508,7 @@ struct TypeInfo >>> void (*class_base_init)(ObjectClass *klass, const void *data); >>> const void *class_data; >>> >>> - bool (*is_available)(void); >>> + TypeIsAvailable *is_available; >>> const InterfaceInfo *interfaces; >>> }; >>> >>> diff --git a/qom/object.c b/qom/object.c >>> index 96498f3d001..253b9562b41 100644 >>> --- a/qom/object.c >>> +++ b/qom/object.c >>> @@ -15,6 +15,7 @@ >>> #include "qom/compat-properties.h" >>> #include "qom/object.h" >>> #include "qom/object_interfaces.h" >>> +#include "qemu/target-info.h" >>> #include "qemu/cutils.h" >>> #include "qemu/memalign.h" >>> #include "qapi/visitor.h" >>> @@ -167,7 +168,7 @@ static TypeImpl *type_register_internal(const TypeInfo >>> *info) >>> abort(); >>> } >>> >>> - if (info->is_available && !info->is_available()) { >>> + if (info->is_available && !info->is_available(target_info())) { >>> return NULL; >>> } >>> >> >> ``` >> info->is_available(target_info()) >> ``` >> >> or >> >> ``` >> is_available() { >> TargetInfo ti * = target_info(); >> ... >> } >> ``` >> >> Are doing the exact same thing today. >> >> So what is the future goal requiring to introduce this? > > From Daniel P. Berrangé's > requesthttps://lore.kernel.org/qemu-devel/[email protected]/ > I forgot to mention that this is also pretty important for making > introspection work, as we need to be able to say > > 'qemu-system --machine none -qmp ...' > > and connect to QMP to introspect the binary. Having to add a > '--target <name>' into that mix is undesirable, as it creates > a chicken & egg problem. You don't know what targets are built > into qemu-system without introspecting it and you can't > introspect it without selecting a target to introspect. > > From Pierrick's review > https://lore.kernel.org/qemu-devel/[email protected]/So, > for existing binary: -M virt works as before. > > For new multi binary: > $ qemu-system -M virt: > Multiple machines were found, select one among: > - aarch64-virt > - riscv64-virt > > Does it matches what you would expect? > > From Daniel's review > https://lore.kernel.org/qemu-devel/[email protected]/ > We already have 'QemuTargetInfo' struct which is used > with 'query-target', that should also be used with the > new 'query-targets' command. > > We need to add the 'endianness' field to QemuTargetInfo. > > I don't think that we need to report machines though. > We already have 'query-machines' which gives much broader > information on the machines. "MachineInfo" needs to > gain > > "targets": ["SysEmuTarget"] > > to list which target(s) a machine can be used with. > > > To achieve these, we needs add TypeInfo parameter to it so that we can do > > static void report_unsupported_machine_type(const char *name, Error **errp) > { > g_autoptr(GSList) machines = machine_class_get_list(true); > g_autoptr(GString) targets = g_string_new(NULL); > TargetInfoNode *node; > GSList *el; > > error_setg(errp, "unsupported machine type: \"%s\" for target \"%s\"", > name, target_name()); > QLIST_FOREACH(node, target_info_list(), next) { > for (el = machines; el; el = el->next) { > MachineClass *mc = el->data; > > if ((!strcmp(mc->name, name) || !g_strcmp0(mc->alias, name)) && > object_class_get_is_available(OBJECT_CLASS(mc))(node->info)) { > g_string_append_printf(targets, " %s\n", > node->info->target_name); > break; > } > } > } > if (targets->len) { > error_append_hint(errp, "Available for targets:\n%s", targets->str); > } > } > > That is we can iterate on all target-list, and check if it's can be fitlered. >
Ok, I finally see where this is going. So, based on all the previous conversations, we agreed to have a qemu-system binary with all the QOM types available (for all targets). I personally think that if we go this way, we should not have any -target option, and even less a -target none option. The current is_available() approach was made with filtering per target in mind, which predates where things are now. So, it's a good time to reevaluate how to do it. This leaves us with (at least) two options: - keep the callback and add TargetInfo parameter (what is done here) - remove is_available, and adopt a more declarative approach How about we (re)-explore the second one? It's what we did in the past (https://gitlab.com/qemu-project/qemu/-/commit/5de9216064d32eaac125dac4de1878486c16d73e), and that I removed recently, in favor of is_available. My rationale was that it was incomplete, since we needed to filter types per config also, and not only target. Now that direction is to not filter anything, filter per config is unneeded, and switching back to declarative instead of callback makes total sense. Using interfaces like we did has its own issues, and I would not like to see this coming back. I'll do one very concrete proposal: ``` How about letting machines (and machines only first), have a new field 'targets', being a uint32_t mask with an array of EMU_TARGET? machine->targets = EMU_TARGET_X | EMU_TARGET_Y; ``` @Daniel, IIUC, this is exactly the approach you proposed a few weeks ago, just before I got frustrated and lost my patience against you. I think it's more clear for me where you wanted to go. Sorry it took such a large detour. Yonggang, does that sounds good for you? Daniel, does that sounds good for you also? Regards, Pierrick
