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osdep: Change default value of qemu_hw_version() to "2.5+"

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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>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Eduardo Habkost 2015-11-12 15:29:54 -02:00 committed by Michael S. Tsirkin
parent 541abd10a0
commit fac862ffa6
3 changed files with 17 additions and 1 deletions
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5
include/hw/boards.h
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@ -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 >*/

4
include/qemu/osdep.h
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@ -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);

9
util/osdep.c
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@ -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)
{