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Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties |
Date: |
Mon, 22 Sep 2014 14:55:17 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 |
Il 22/09/2014 14:34, Michael S. Tsirkin ha scritto:
> On Mon, Sep 22, 2014 at 02:06:38PM +0200, Paolo Bonzini wrote:
>> Il 22/09/2014 13:22, Gonglei (Arei) ha scritto:
>>>> This doesn't change the fact that ObjectProperty is a generic struct,
>>>> and adding alias-specific fields there is wrong.
>>>
>>> OK, Maybe I should find other ways to attach this purpose and
>>> avoid layering violation. Thanks!
>>
>> Unfortunately I cannot think of any.
>>
>> We could add a description field to ObjectProperty, and replace
>> legacy_name with a description. The output then would be
>>
>> virtio-blk.drive=str (drive)
>> That's a bit hackish, but perhaps it would be good enough for mst and
>> Markus?
>
> I would just drop "str" and replace it with drive.
In the above example, the format would be
CLASS.PROPERTY=TYPE (DESCRIPTION)
where I just put "drive" as the description to resemble the old output.
You cannot just have
foo.drive=drive
because the type is *not* "drive", it's "str" (if anything, we could
make it link<BlockBackend> which does not really show the connection
between BlockBackend and -drive).
The problem is that "drive" as the type (the legacy_name) is simply not
available for the virtio-blk-pci.drive property. It's hidden beneath an
opaque pointer. Gonglei's patches were adding fields to ObjectProperty
just to avoid visiting that opaque pointer, which I consider a layering
violation.
> I seems to convey zero information.
> Description should be something more informative, e.g.
> (ID of a drive to use as a backend)
That would of course be fine too. The problem is then that we have 644
properties (DEFINE_PROP_* macro invocations) that someone must add a
description to.
> Help for -device could add "Must match ID of a -drive option".
> Help for device HMP command could add "Must match ID of a drive command."
You are turning a bug that nobody noticed until now, and that really
doesn't break anything, into a month or more worth of work.
Paolo
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, (continued)
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Michael S. Tsirkin, 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Gonglei (Arei), 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Paolo Bonzini, 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Gonglei (Arei), 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Paolo Bonzini, 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Gonglei (Arei), 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Paolo Bonzini, 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Michael S. Tsirkin, 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Gonglei (Arei), 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Paolo Bonzini, 2014/09/23
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Gonglei (Arei), 2014/09/23
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Markus Armbruster, 2014/09/23
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Markus Armbruster, 2014/09/23
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Michael S. Tsirkin, 2014/09/23
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Gonglei (Arei), 2014/09/23
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Markus Armbruster, 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Gonglei (Arei), 2014/09/22
- Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties, Paolo Bonzini, 2014/09/22