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Date:   Wed, 5 Jun 2019 12:09:42 +0200
From:   "kraxel@redhat.com" <kraxel@redhat.com>
To:     "Zhang, Tina" <tina.zhang@intel.com>
Cc:     Zhenyu Wang <zhenyuw@linux.intel.com>,
        "intel-gvt-dev@lists.freedesktop.org" 
        <intel-gvt-dev@lists.freedesktop.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Lv, Zhiyuan" <zhiyuan.lv@intel.com>,
        "Wang, Zhi A" <zhi.a.wang@intel.com>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        "Yuan, Hang" <hang.yuan@intel.com>,
        "alex.williamson@redhat.com" <alex.williamson@redhat.com>
Subject: Re: [RFC PATCH v2 1/3] vfio: Use capability chains to handle device
 specific irq
Message-ID: <20190605100942.bceke6yqjynuwk3z@sirius.home.kraxel.org>
References: <20190604095534.10337-1-tina.zhang@intel.com>
 <20190604095534.10337-2-tina.zhang@intel.com>
 <20190605040446.GW9684@zhen-hp.sh.intel.com>
 <237F54289DF84E4997F34151298ABEBC87646B5C@SHSMSX101.ccr.corp.intel.com>
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  Hi,

> > Really need to split for different planes? I'd like a
> > VFIO_IRQ_SUBTYPE_GFX_DISPLAY_EVENT
> > so user space can probe change for all.

> User space can choose to user different handlers according to the
> specific event. For example, user space might not want to handle every
> cursor event due to performance consideration. Besides, it can reduce
> the probe times, as we don't need to probe twice to make sure if both
> cursor plane and primary plane have been updated.

I'd suggest to use the value passed via eventfd for that, i.e. instead
of sending "1" unconditionally send a mask of changed planes.

cheers,
  Gerd