From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Markus Armbruster" <armbru@redhat.com>,
qemu-devel@nongnu.org, "Don Slutz" <dslutz@verizon.com>,
"Luiz Capitulino" <lcapitulino@redhat.com>,
"Anthony Liguori" <aliguori@amazon.com>,
"Andreas Färber" <afaerber@suse.de>,
"Richard Henderson" <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH v7 0/9] Add limited support of VMware's hyper-call rpc
Date: Wed, 17 Jun 2015 18:48:40 +0200 [thread overview]
Message-ID: <5581A4E8.8080505@redhat.com> (raw)
In-Reply-To: <20150617182322-mutt-send-email-mst@redhat.com>
On 17/06/2015 18:29, Michael S. Tsirkin wrote:
> On Wed, Jun 17, 2015 at 06:17:19PM +0200, Paolo Bonzini wrote:
>>
>>
>> On 17/06/2015 16:29, Michael S. Tsirkin wrote:
>>> On Wed, Jun 17, 2015 at 04:27:13PM +0200, Paolo Bonzini wrote:
>>>>
>>>>
>>>> On 17/06/2015 16:18, Michael S. Tsirkin wrote:
>>>>>>> Yes, that's what was done for parallel and pcspk as well. There's no
>>>>>>> infrastructure to avoid it.
>>>>>>>
>>>>>>> Paolo
>>>>> How do you mean? We have multiple ways to keep devices
>>>>> compatible with old versions.
>>>>> Set a new property to skip the extra stuff.
>>>>
>>>> Not if the device didn't have a vmstate at all, unfortunately.
>>>
>>> Skip creating the device completely for old machine types.
>>
>> Which device? The vmstate is tied to the same device that has always
>> been created.
>
> Just disable the new functionality. Make it behave in
> a compatible way.
Ok. Doesn't solve the fact that the migration stream changes just
because dc->vmsd was NULL and now isn't. We cannot add a subsection:
there is no toplevel section for it to hang it from.
>> we enable this thing by default (why do we?)
>
> Sigh. There is a very simple way to add a device in qemu: let user
> request it with -device. If one does this, one gets to maintain the
> resulting mess without bothering with pc maintainers in any way.
>
> But of course, everyone implementing a new feature feels it's such a
> great thing, and completel zero risk, it must be part of the default
> machine. Guess what, one then gets to bother with versioning from day 0.
>
> I don't see what you are saying. Suddenly guest visible
> changes within a machine type are ok?
Some are. They have always been. For example, the 0xcf9 reset was
added without backwards compatibility. Bug fixes are also guest visible.
Also, commands are added unconditionally, with only the configuration
bits that govern discovery being masked. That's also guest visible if
the guest doesn't follow the spec.
> So we have a bug, need to fix it, preferably before piling up
> more features. The best way imho is for 2.4 to avoid
> this device unless requested explicitly.
The device is already enabled by default. It grew new functionality
(before it was basically just for the mouse). It didn't have state. It
now has.
Paolo
next prev parent reply other threads:[~2015-06-17 16:48 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-12 14:05 [Qemu-devel] [PATCH v7 0/9] Add limited support of VMware's hyper-call rpc Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [BUGFIX][PATCH v7 1/9] vmport: The io memory region needs to be at least a size of 4 Don Slutz
2015-06-12 22:38 ` Eric Blake
2015-06-15 13:53 ` Don Slutz
2015-06-15 15:09 ` Eric Blake
2015-06-15 16:15 ` Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [PATCH v7 2/9] vmport: Switch to trace Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [BUGFIX][PATCH v7 3/9] vmport: Fix vmport_cmd_ram_size Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [PATCH v7 4/9] vmport_rpc: Add the object vmport_rpc Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [PATCH v7 5/9] vmport_rpc: Add limited support of VMware's hyper-call rpc Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [PATCH v7 6/9] vmport_rpc: Add QMP access to vmport_rpc object Don Slutz
2015-06-15 15:53 ` Eric Blake
2015-06-17 16:42 ` Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [PATCH v7 7/9] vmport_rpc: Add migration Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [PATCH v7 8/9] vmport: Add VMware all ring hack Don Slutz
2015-06-12 14:05 ` [Qemu-devel] [PATCH v7 9/9] MAINTAINERS: add VMware port Don Slutz
2015-06-17 13:44 ` [Qemu-devel] [PATCH v7 0/9] Add limited support of VMware's hyper-call rpc Paolo Bonzini
2015-06-17 22:26 ` Don Slutz
2015-06-18 7:58 ` Michael S. Tsirkin
2015-06-18 8:33 ` Paolo Bonzini
2015-06-18 9:40 ` Michael S. Tsirkin
2015-06-18 8:33 ` Paolo Bonzini
2015-06-17 14:11 ` Michael S. Tsirkin
2015-06-17 14:13 ` Paolo Bonzini
2015-06-17 14:18 ` Michael S. Tsirkin
2015-06-17 14:27 ` Paolo Bonzini
2015-06-17 14:29 ` Michael S. Tsirkin
2015-06-17 16:17 ` Paolo Bonzini
2015-06-17 16:29 ` Michael S. Tsirkin
2015-06-17 16:48 ` Paolo Bonzini [this message]
2015-06-17 18:43 ` Michael S. Tsirkin
2015-06-17 19:15 ` Paolo Bonzini
2015-06-17 19:22 ` Michael S. Tsirkin
2015-06-17 19:24 ` Paolo Bonzini
2015-06-17 19:29 ` Michael S. Tsirkin
2015-06-17 17:03 ` Don Slutz
2015-06-17 17:14 ` Paolo Bonzini
2015-06-17 17:25 ` Paolo Bonzini
2015-06-17 17:34 ` Don Slutz
2015-06-17 18:58 ` Michael S. Tsirkin
2015-06-18 18:40 ` Don Slutz
2015-06-17 18:45 ` Michael S. Tsirkin
2015-06-17 18:45 ` Michael S. Tsirkin
2015-06-18 7:03 ` Gerd Hoffmann
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