From fac862ffa605f6fa41f52033b27346d26a96bea5 Mon Sep 17 00:00:00 2001 From: Eduardo Habkost Date: Thu, 12 Nov 2015 15:29:54 -0200 Subject: [PATCH] osdep: Change default value of qemu_hw_version() to "2.5+" 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 Signed-off-by: Eduardo Habkost Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- include/hw/boards.h | 5 +++++ include/qemu/osdep.h | 4 ++++ util/osdep.c | 9 ++++++++- 3 files changed, 17 insertions(+), 1 deletion(-) diff --git a/include/hw/boards.h b/include/hw/boards.h index 24eb6f0e77..5da4fb00ee 100644 --- a/include/hw/boards.h +++ b/include/hw/boards.h @@ -51,6 +51,11 @@ 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 >*/ diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 861d84b4e4..84e84ac700 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -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); diff --git a/util/osdep.c b/util/osdep.c index 80c6bfeeb2..534b51147c 100644 --- a/util/osdep.c +++ b/util/osdep.c @@ -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) {