Re: [Qemu-devel] [BUGFIX][PATCH for 2.2 1/1] hw/i386/pc_piix.c: Also pass vmport=off for xenfv machine

[Eduardo Habkost]

On Wed, Nov 19, 2014 at 02:08:08PM -0500, Don Slutz wrote:
> 
> On 11/19/14 13:08, Paolo Bonzini wrote:
> >
> >On 19/11/2014 19:07, Don Slutz wrote:
> >>>"-M pc -machine accel=xen" should work and, if that's what you want,
> >>>disable the vmport device.  I think this patch is wrong.
> >>>
> >>>Paolo
> >>Well, I also want "-M pc -machine accel=xen,vmport=on" to work.
> >Right.  So let's start by deciding what the desired semantics are for
> >all six cases: -M pc/xenfv, -machine vmport=on/off/absent.
> >
> >Paolo
> 
> I get 12 cases (PCMachineState *pcms = PC_MACHINE(obj)):

We have more cases, if we consider "-M pc-2.1" too.

With this first patch (the one changing default_machine_opts), I expect
to get the following results:

-M pc
    pcms->vmport is true
-M pc -machine vmport=on
    pcms->vmport is true
-M pc -machine vmport=off
    pcms->vmport is false
-M pc-2.1
    pcms->vmport is true
-M pc-2.1 -machine vmport=on
    pcms->vmport is true
    (but it doesn't matter, QEMU 2.1 didn't have the vmport option)
-M pc-2.1 -machine vmport=off
    pcms->vmport is false
    (but it doesn't matter, QEMU 2.1 didn't have the vmport option)
-M xenfv
    pcms->vmport is false
-M xenfv -machine vmport=on
    pcms->vmport is true
-M xenfv -machine vmport=off
    pcms->vmport is false

-M pc -machine accel=xen
    pcms->vmport is true
-M pc -machine vmport=on,accel=xen
    pcms->vmport is true
-M pc -machine vmport=off,accel=xen
    pcms->vmport is false
-M pc-2.1 -machine accel=xen
    pcms->vmport is true **
-M pc-2.1 -machine vmport=on,accel=xen
    pcms->vmport is true
    (but it doesn't matter, QEMU 2.1 didn't have the vmport option)
-M pc-2.1 -machine vmport=off,accel=xen
    pcms->vmport is false
    (but it doesn't matter, QEMU 2.1 didn't have the vmport option)
-M xenfv -machine accel=xen
    pcms->vmport is false
-M xenfv -machine vmport=on,accel=xen
    pcms->vmport is true
-M xenfv -machine vmport=off,accel=xen
    pcms->vmport is false

I believe there's no consensus yet about the one marked with "**" above. It
boils to the question: do we need to keep guest ABI stability when using
"-M pc-2.1 -machine accel=xen"?

-- 
Eduardo