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From: "Andreas Färber" <afaerber@suse.de>
To: Michael Mueller <mimu@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org,
	"Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
	Peter Crosthwaite <peter.crosthwaite@xilinx.com>,
	linux-s390@vger.kernel.org, kvm@vger.kernel.org,
	Gleb Natapov <gleb@kernel.org>, Alexander Graf <agraf@suse.de>,
	Eduardo Habkost <ehabkost@redhat.com>,
	linux-kernel@vger.kernel.org,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	"Jason J. Herne" <jjherne@linux.vnet.ibm.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Alistair Francis <alistair.francis@xilinx.com>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH v3 01/16] Introduce probe mode for machine type none
Date: Mon, 02 Mar 2015 17:57:01 +0100	[thread overview]
Message-ID: <54F4965D.7000701@suse.de> (raw)
In-Reply-To: <20150302174352.3715f1e4@bee>

Am 02.03.2015 um 17:43 schrieb Michael Mueller:
> On Mon, 02 Mar 2015 14:57:21 +0100
> Andreas Färber <afaerber@suse.de> wrote:
> 
>>>  int configure_accelerator(MachineState *ms)
>>>  {
>>> -    const char *p;
>>> +    const char *p, *name;
>>>      char buf[10];
>>>      int ret;
>>>      bool accel_initialised = false;
>>>      bool init_failed = false;
>>>      AccelClass *acc = NULL;
>>> +    ObjectClass *oc;
>>> +    bool probe_mode = false;
>>>  
>>>      p = qemu_opt_get(qemu_get_machine_opts(), "accel");
>>>      if (p == NULL) {
>>> -        /* Use the default "accelerator", tcg */
>>> -        p = "tcg";
>>> +        oc = (ObjectClass *) MACHINE_GET_CLASS(current_machine);
>>> +        name = object_class_get_name(oc);
>>> +        probe_mode = !strcmp(name, "none" TYPE_MACHINE_SUFFIX);
>>> +        if (probe_mode) {
>>> +            /* Use these accelerators in probe mode, tcg should be last */
>>> +            p = probe_mode_accels;
>>> +        } else {
>>> +            /* Use the default "accelerator", tcg */
>>> +            p = "tcg";
>>> +        }
>>>      }  
>>
>> Can't we instead use an explicit ,accel=probe or ,accel=auto?
>> That would then obsolete the next patch.
> 
> How would you express the following with the accel=<pseudo-accel> approach?
> 
> -probe -machine s390-ccw,accel=kvm 
> 
> Using machine "none" as default with tcg as last accelerator initialized should not break
> anything.
> 
> -M none

Let me ask differently: What does -machine none or -M none have to do
with probing? It reads as if you are introducing two probe modes. Why do
you need both? If we have -probe, isn't that independent of which
machine we specify? Who is going to call either, with which respective goal?

I think that changing the semantics of an absent ,accel=foo parameter to
mean something else than its longtime default of tcg is a bad idea.

Have you testing qtest with it? Doesn't -qtest imply accel=qtest or is
that always passed explicitly?

Regards,
Andreas

-- 
SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Jennifer Guild, Dilip Upmanyu,
Graham Norton; HRB 21284 (AG Nürnberg)

  reply	other threads:[~2015-03-02 16:57 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-02 12:43 [PATCH v3 00/16] s390x cpu model implementation Michael Mueller
2015-03-02 12:43 ` [PATCH v3 01/16] Introduce probe mode for machine type none Michael Mueller
2015-03-02 13:57   ` Andreas Färber
2015-03-02 16:43     ` [Qemu-devel] " Michael Mueller
2015-03-02 16:57       ` Andreas Färber [this message]
2015-03-03 10:55         ` Michael Mueller
2015-03-04 19:19           ` Eduardo Habkost
2015-03-05 14:56             ` Michael Mueller
2015-03-05 15:07               ` Eduardo Habkost
2015-03-02 19:17   ` Eduardo Habkost
2015-03-03 10:23     ` [Qemu-devel] " Michael Mueller
2015-03-02 12:43 ` [PATCH v3 02/16] Introduce option --probe to switch into probe mode Michael Mueller
2015-03-02 12:43 ` [PATCH v3 03/16] Introduce stub routine cpu_desc_avail Michael Mueller
2015-03-02 12:43 ` [PATCH v3 04/16] target-s390x: Introduce cpu facilities Michael Mueller
2015-03-02 12:43 ` [PATCH v3 05/16] target-s390x: Generate facility defines per cpu model Michael Mueller
2015-03-02 12:43 ` [PATCH v3 06/16] target-s390x: Introduce cpu models Michael Mueller
2015-03-02 12:43 ` [PATCH v3 07/16] target-s390x: Define cpu model specific facility lists Michael Mueller
2015-03-02 12:44 ` [PATCH v3 08/16] target-s390x: Add cpu model alias definition routines Michael Mueller
2015-03-02 12:44 ` [PATCH v3 09/16] target-s390x: Update linux-headers/asm-s390/kvm.h Michael Mueller
2015-03-02 12:44 ` [PATCH v3 10/16] target-s390x: Add KVM VM attribute interface for cpu models Michael Mueller
2015-03-02 12:44 ` [PATCH v3 11/16] target-s390x: Add cpu class initialization routines Michael Mueller
2015-03-02 12:44 ` [PATCH v3 12/16] target-s390x: Prepare accelerator during cpu object realization Michael Mueller
2015-03-02 12:44 ` [PATCH v3 13/16] target-s390x: New QMP command query-cpu-model Michael Mueller
2015-03-02 12:44 ` [PATCH v3 14/16] target-s390x: Extend QMP command query-cpu-definitions Michael Mueller
2015-03-02 19:11   ` Eduardo Habkost
2015-03-04  9:00     ` [Qemu-devel] " Michael Mueller
2015-03-02 12:44 ` [PATCH v3 15/16] target-s390x: Introduce facility test routine Michael Mueller
2015-03-02 12:44 ` [PATCH v3 16/16] target-s390x: Enable cpu model usage Michael Mueller
2015-03-02 19:25 ` [PATCH v3 00/16] s390x cpu model implementation Eduardo Habkost

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