@@ -52,6 +52,11 @@ bool machine_mem_merge(MachineState *machine);
* used to provide @cpu_index to socket number mapping, allowing
* a machine to group CPU threads belonging to the same socket/package
* Returns: socket number given cpu_index belongs to.
+ * @hw_version:
+ * Value of QEMU_VERSION when the machine was added to QEMU.
+ * Set only by old machines because they need to keep
+ * compatibility on code that exposed QEMU_VERSION to guests in
+ * the past (and now use qemu_hw_version()).
*/
struct MachineClass {
/*< private >*/
@@ -256,6 +256,10 @@ static inline void qemu_timersub(const struct timeval *val1,
void qemu_set_cloexec(int fd);
+/* QEMU "hardware version" setting. Used to replace code that exposed
+ * QEMU_VERSION to guests in the past and need to keep compatibilty.
+ * Do not use qemu_hw_version() in new code.
+ */
void qemu_set_hw_version(const char *);
const char *qemu_hw_version(void);
@@ -52,7 +52,14 @@ extern int madvise(caddr_t, size_t, int);
static bool fips_enabled = false;
-static const char *hw_version = QEMU_VERSION;
+/* Starting on QEMU 2.5, qemu_hw_version() returns "2.5+" by default
+ * instead of QEMU_VERSION, so setting hw_version on MachineClass
+ * is no longer mandatory.
+ *
+ * Do NOT change this string, or it will break compatibility on all
+ * machine classes that don't set hw_version.
+ */
+static const char *hw_version = "2.5+";
int socket_set_cork(int fd, int v)
{
There are two issues with qemu_hw_version() today: 1) If a machine has hw_version set, the value returned by it is not very useful, because it is not the actual QEMU version. 2) If a machine does't set hw_version, the return value of qemu_hw_version() is broken, because it will change when upgrading QEMU. For those reasons, using qemu_hw_version() is strongly discouraged, and should be used only in code that used QEMU_VERSION in the past and needs to keep compatibility. To fix (2), instead of making every machine broken by default unless they set hw_version, make qemu_hw_version() simply return "2.5+" if qemu_set_hw_version() is not called. Suggested-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- include/hw/boards.h | 5 +++++ include/qemu/osdep.h | 4 ++++ util/osdep.c | 9 ++++++++- 3 files changed, 17 insertions(+), 1 deletion(-)