On 4/17/25 17:50, Philippe Mathieu-Daudé wrote:
Binaries can register a QOM type to filter their machines
by filling their TargetInfo::machine_typename field.
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
include/qemu/target_info-impl.h | 3 +++
include/qemu/target_info.h | 8 ++++++++
system/vl.c | 14 ++++++++++++++
target_info.c | 5 +++++
4 files changed, 30 insertions(+)
diff --git a/include/qemu/target_info-impl.h b/include/qemu/target_info-impl.h
index d5c94ed5296..990fb067d20 100644
--- a/include/qemu/target_info-impl.h
+++ b/include/qemu/target_info-impl.h
@@ -16,6 +16,9 @@ typedef struct TargetInfo {
/* runtime equivalent of TARGET_NAME definition */
const char *const name;
+ /* QOM typename machines for this binary must implement */
+ const char *const machine_typename;
+
} TargetInfo;
const TargetInfo *target_info(void);
diff --git a/include/qemu/target_info.h b/include/qemu/target_info.h
index 3f6cbbbd300..e9fd2fdd7b0 100644
--- a/include/qemu/target_info.h
+++ b/include/qemu/target_info.h
@@ -16,4 +16,12 @@
*/
const char *target_name(void);
+/**
+ * target_machine_interface_typename:
+ *
+ * Returns: Name of the QOM interface implemented by machines
+ * usable on this target binary.
+ */
+const char *target_machine_interface_typename(void);
+
#endif
diff --git a/system/vl.c b/system/vl.c
index d8a0fe713c9..4e43e55afe7 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -27,6 +27,7 @@
#include "qemu/datadir.h"
#include "qemu/units.h"
#include "qemu/module.h"
+#include "qemu/target_info.h"
#include "exec/cpu-common.h"
#include "exec/page-vary.h"
#include "hw/qdev-properties.h"
@@ -836,11 +837,17 @@ static bool usb_parse(const char *cmdline, Error **errp)
static MachineClass *find_machine(const char *name, GSList *machines)
{
GSList *el;
+ const char *qom_typename_filter = target_machine_interface_typename();
for (el = machines; el; el = el->next) {
MachineClass *mc = el->data;
if (!strcmp(mc->name, name) || !g_strcmp0(mc->alias, name)) {
+ if (qom_typename_filter
+ && !object_class_dynamic_cast(el->data, qom_typename_filter)) {
+ /* Machine is not for this binary: fail */
+ return NULL;
+ }
return mc;
}
}
@@ -1563,6 +1570,7 @@ static void machine_help_func(const QDict *qdict)
g_autoptr(GSList) machines = NULL;
GSList *el;
const char *type = qdict_get_try_str(qdict, "type");
+ const char *qom_typename_filter = target_machine_interface_typename();
machines = object_class_get_list(TYPE_MACHINE, false);
We can replace change to system/vl.c with:
const char *machine_type = target_machine_interface_typename();
machines = object_class_get_list(machine_type, false);
if (type) {
@@ -1577,6 +1585,12 @@ static void machine_help_func(const QDict *qdict)
machines = g_slist_sort(machines, machine_class_cmp);
for (el = machines; el; el = el->next) {
MachineClass *mc = el->data;
+
+ if (qom_typename_filter
+ && !object_class_dynamic_cast(el->data, qom_typename_filter)) {
+ /* Machine is not for this binary: skip */
+ continue;
+ }
if (mc->alias) {
printf("%-20s %s (alias of %s)\n", mc->alias, mc->desc, mc->name);
}
diff --git a/target_info.c b/target_info.c
index 877a6a15014..226eed1fd7d 100644
--- a/target_info.c
+++ b/target_info.c
@@ -14,3 +14,8 @@ const char *target_name(void)
{
return target_info()->name;
}
+
+const char *target_machine_interface_typename(void)
+{
+ return target_info()->machine_typename;
And here:
const char *machine_type = target_info()->machine_typename;
if (!machine_type) {
machine_type = TYPE_MACHINE;
}
return machine_type;
+}
This way, there is no special case to handle anywhere, and we can safely
replace occurrences of TYPE_MACHINE queries with
target_machine_interface_typename().
As well, just a nit, but it's not important to know it's an interface, I
would prefer a simpler name: target_machine_type();
