Re: [Qemu-devel] [PATCH 03/10] target-i386: move hyperv_* static globals to CPUState

[Igor Mammedov]

On Tue, 26 Feb 2013 11:50:23 -0300
Eduardo Habkost <address@hidden> wrote:

> On Mon, Feb 25, 2013 at 02:03:02AM +0100, Igor Mammedov wrote:
> > - since hyperv_* helper functions are used only in target-i386/kvm.c
> >   move them there as static helpers
> > 
> > Signed-off-by: Igor Mammedov <address@hidden>
> > Requestd-By: Eduardo Habkost <address@hidden>
> 
> I wonder if we could do this later, to make review and testing easier.
> We could simply keep the hv_* handling inside parse_featurestr() by now.
> I don't think this would block any of the CPU hotplug or CPU model
> probing/compatibility/reliability work we're doing. I mean:
device_add from CPU hot-add POV would be usable once we have all features
accepted on -cpu converted to properties + sub-classes.

> 
> * I don't expect hv-* to appear on a machine-type compat_props array in
>   the near feature.
> * I don't expect people to need to set per-CPU hv-* properties on
>   device_add for CPU hotplug.
> 
> So we could keep them as special cases on parse_featurestr(), and
> convert them to per-CPU properties only after we have the subclasses and
> CPU hotplug working.
it won't be a consistent interface, where user who has 
"-cpu XXX,+foo1,+hv_spinlocks,+foo2" on cmd-line
would have to use "device_add XXX,foo1=true,foo2=true" manually excluding
options from device_add, i.e. it propagates special casing to users as
well. And when hv_ are moved to per-CPU fields, it might break users since
they will still exclude some options.

> 
> Considering that -cpu options will be translated to global properties,
> it will be trivial to keep compatibility with existing behavior of "-cpu
> hv_*=..." once we change them from static variables to per-CPU fields.
Global properties would just allow not to specify foo1,foo2 on
device_add from hot-plug POV.

If this and following patch are to complex we could fallback to alternative
from v6 for hv_* features, which produce the same external property interface
just with different internal approach.

> 
> > ---
> >  target-i386/Makefile.objs |    2 +-
> >  target-i386/cpu.c         |   16 +++++++---
> >  target-i386/cpu.h         |    7 +++++
> >  target-i386/hyperv.c      |   64
> > --------------------------------------------- target-i386/hyperv.h
> > |   45 ------------------------------- target-i386/kvm.c         |   36
> > ++++++++++++++++++------- 6 files changed, 45 insertions(+), 125
> > deletions(-) delete mode 100644 target-i386/hyperv.c
> >  delete mode 100644 target-i386/hyperv.h
> > 
> [...]
>