[Qemu-devel] [PATCH 0/2] Don't require hw_version to be set on every machine

[Qemu-devel] [PATCH 0/2] Don't require hw_version to be set on every machine

[Eduardo Habkost]

This changes the qemu_hw_version() default to "2.5+" so we don't
make every machine class broken by default unless they set
hw_version.

For reference, these are the current users of qemu_hw_version():

hw/arm/nseries.c:    pstrcat((void *) w, 12, qemu_hw_version()); /* char version[12] */
hw/ide/core.c:        pstrcpy(s->version, sizeof(s->version), qemu_hw_version());
hw/scsi/megasas.c:    snprintf(info.package_version, 0x60, "%s-QEMU", qemu_hw_version());
hw/scsi/scsi-bus.c:        pstrcpy((char *) &r->buf[32], 4, qemu_hw_version());
hw/scsi/scsi-disk.c:        s->version = g_strdup(qemu_hw_version());
target-i386/cpu.c:                        qemu_hw_version());

Cc: Andrzej Zaborowski <balrogg@gmail.com>
Cc: John Snow <jsnow@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Richard Henderson <rth@twiddle.net>

Eduardo Habkost (2):
  osdep: Change default value of qemu_hw_version() to "2.5+"
  pc: Don't set hw_version on pc-*-2.5

 hw/i386/pc_piix.c    | 1 -
 hw/i386/pc_q35.c     | 1 -
 include/hw/boards.h  | 5 +++++
 include/qemu/osdep.h | 4 ++++
 util/osdep.c         | 9 ++++++++-
 5 files changed, 17 insertions(+), 3 deletions(-)

-- 
2.1.0

[Qemu-devel] [PATCH 1/2] osdep: Change default value of qemu_hw_version() to "2.5+"

[Eduardo Habkost]

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(-)

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 3e9a92c..51906af 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -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 >*/
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 861d84b..84e84ac 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 80c6bfe..534b511 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)
 {
-- 
2.1.0

[Qemu-devel] [PATCH 2/2] pc: Don't set hw_version on pc-*-2.5

[Eduardo Habkost]

Now that qemu_hw_version() returns a fixed "2.5+" string instead
of QEMU_VERSION, we don't need to set hw_version on pc-*-2.5
explicitly.

Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 hw/i386/pc_piix.c | 1 -
 hw/i386/pc_q35.c  | 1 -
 2 files changed, 2 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 07d0baa..2e41efe 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -472,7 +472,6 @@ static void pc_i440fx_machine_options(MachineClass *m)
 static void pc_i440fx_2_5_machine_options(MachineClass *m)
 {
     pc_i440fx_machine_options(m);
-    m->hw_version = QEMU_VERSION;
     m->alias = "pc";
     m->is_default = 1;
 }
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 0fdae09..133bc68 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -373,7 +373,6 @@ static void pc_q35_machine_options(MachineClass *m)
 static void pc_q35_2_5_machine_options(MachineClass *m)
 {
     pc_q35_machine_options(m);
-    m->hw_version = QEMU_VERSION;
     m->alias = "q35";
 }
 
-- 
2.1.0

Re: [Qemu-devel] [PATCH 0/2] Don't require hw_version to be set on every machine

[Eduardo Habkost]

Ping? Any thoughts on this approach?

-rc2 is too late for this kind of change, maybe?


On Thu, Nov 12, 2015 at 03:29:53PM -0200, Eduardo Habkost wrote:
> This changes the qemu_hw_version() default to "2.5+" so we don't
> make every machine class broken by default unless they set
> hw_version.
> 
> For reference, these are the current users of qemu_hw_version():
> 
> hw/arm/nseries.c:    pstrcat((void *) w, 12, qemu_hw_version()); /* char version[12] */
> hw/ide/core.c:        pstrcpy(s->version, sizeof(s->version), qemu_hw_version());
> hw/scsi/megasas.c:    snprintf(info.package_version, 0x60, "%s-QEMU", qemu_hw_version());
> hw/scsi/scsi-bus.c:        pstrcpy((char *) &r->buf[32], 4, qemu_hw_version());
> hw/scsi/scsi-disk.c:        s->version = g_strdup(qemu_hw_version());
> target-i386/cpu.c:                        qemu_hw_version());
> 
> Cc: Andrzej Zaborowski <balrogg@gmail.com>
> Cc: John Snow <jsnow@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Richard Henderson <rth@twiddle.net>
> 
> Eduardo Habkost (2):
>   osdep: Change default value of qemu_hw_version() to "2.5+"
>   pc: Don't set hw_version on pc-*-2.5
> 
>  hw/i386/pc_piix.c    | 1 -
>  hw/i386/pc_q35.c     | 1 -
>  include/hw/boards.h  | 5 +++++
>  include/qemu/osdep.h | 4 ++++
>  util/osdep.c         | 9 ++++++++-
>  5 files changed, 17 insertions(+), 3 deletions(-)
> 
> -- 
> 2.1.0
> 
> 

-- 
Eduardo

Re: [Qemu-devel] [PATCH 0/2] Don't require hw_version to be set on every machine

[Michael S. Tsirkin]

On Mon, Nov 23, 2015 at 10:53:39AM -0200, Eduardo Habkost wrote:
> 
> Ping? Any thoughts on this approach?
> 
> -rc2 is too late for this kind of change, maybe?
> 

I queued this up for 2.5, will merge later this week
unless anyone objects.

> On Thu, Nov 12, 2015 at 03:29:53PM -0200, Eduardo Habkost wrote:
> > This changes the qemu_hw_version() default to "2.5+" so we don't
> > make every machine class broken by default unless they set
> > hw_version.
> > 
> > For reference, these are the current users of qemu_hw_version():
> > 
> > hw/arm/nseries.c:    pstrcat((void *) w, 12, qemu_hw_version()); /* char version[12] */
> > hw/ide/core.c:        pstrcpy(s->version, sizeof(s->version), qemu_hw_version());
> > hw/scsi/megasas.c:    snprintf(info.package_version, 0x60, "%s-QEMU", qemu_hw_version());
> > hw/scsi/scsi-bus.c:        pstrcpy((char *) &r->buf[32], 4, qemu_hw_version());
> > hw/scsi/scsi-disk.c:        s->version = g_strdup(qemu_hw_version());
> > target-i386/cpu.c:                        qemu_hw_version());
> > 
> > Cc: Andrzej Zaborowski <balrogg@gmail.com>
> > Cc: John Snow <jsnow@redhat.com>
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: Hannes Reinecke <hare@suse.de>
> > Cc: Richard Henderson <rth@twiddle.net>
> > 
> > Eduardo Habkost (2):
> >   osdep: Change default value of qemu_hw_version() to "2.5+"
> >   pc: Don't set hw_version on pc-*-2.5
> > 
> >  hw/i386/pc_piix.c    | 1 -
> >  hw/i386/pc_q35.c     | 1 -
> >  include/hw/boards.h  | 5 +++++
> >  include/qemu/osdep.h | 4 ++++
> >  util/osdep.c         | 9 ++++++++-
> >  5 files changed, 17 insertions(+), 3 deletions(-)
> > 
> > -- 
> > 2.1.0
> > 
> > 
> 
> -- 
> Eduardo