From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Tetsuya Mukawa <mukawa@igel.co.jp>
Cc: dev@dpdk.org, jianfeng.tan@intel.com, huawei.xie@intel.com
Subject: Re: [dpdk-dev] [PATCH v2] vhost: Fix default value of kickfd and callfd
Date: Mon, 14 Mar 2016 10:08:58 +0800 [thread overview]
Message-ID: <20160314020858.GJ979@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <56E619C6.6060809@igel.co.jp>
On Mon, Mar 14, 2016 at 10:54:14AM +0900, Tetsuya Mukawa wrote:
> On 2016/03/11 16:19, Yuanhan Liu wrote:
> > On Thu, Mar 10, 2016 at 04:06:05PM +0900, Tetsuya Mukawa wrote:
> >> Currently, default values of kickfd and callfd are -1.
> >> If the values are -1, current code guesses kickfd and callfd haven't
> >> been initialized yet. And vhost library will guess the virtqueue isn't
> >> ready for processing.
> >> But callfd and kickfd will be set as -1 when "--enable-kvm"
> >> isn't specified in QEMU command line. It means we cannot treat -1 as
> >> uninitialized state. The patch changes default values to -2. And the
> >> patch defines -2 as VIRTIO_UNINITIALIZED_EVENTFD.
> > This looks more like a workaround to me.
>
>
> Hi Yuanhan,
>
> Sorry for late reply.
> I have checked QEMU documentation, and found below.
>
> ----------
> * VHOST_USER_SET_VRING_CALL
>
> Id: 14
> Equivalent ioctl: VHOST_SET_VRING_CALL
> Master payload: u64
>
> Set the event file descriptor to signal when buffers are used. It
> is passed in the ancillary data.
> Bits (0-7) of the payload contain the vring index. Bit 8 is the
> invalid FD flag.
> ----------
>
> VHOST_USER_SET_VRING_KICK has almost same description.
> I will check this invalid flag, and if it works for our case, then will
> use it.
> How about it?
Yeah, that indeed sounds much better.
--yliu
>
> > Besides, this patch would make
> > following fail:
> >
> > eventfd_write(vq->callfd, (eventfd_t)1);
>
> It's my fault.
> I thought above case should be blocked by virtio spec itself. So just
> leave it.
> But eventfd is came from vhost spec, so VRING_AVAIL_F_NO_INTERRUPT might
> be set even when kickfd and callfd are -1.
> Thanks for checking it.
>
> Tetsuya
>
> > --yliu
next prev parent reply other threads:[~2016-03-14 2:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-10 6:14 [dpdk-dev] [PATCH] " Tetsuya Mukawa
2016-03-10 6:25 ` Tan, Jianfeng
2016-03-10 6:34 ` Tetsuya Mukawa
2016-03-10 6:39 ` Tan, Jianfeng
2016-03-10 6:42 ` Tetsuya Mukawa
2016-03-10 7:06 ` [dpdk-dev] [PATCH v2] " Tetsuya Mukawa
2016-03-11 7:19 ` Yuanhan Liu
2016-03-14 1:54 ` Tetsuya Mukawa
2016-03-14 2:08 ` Yuanhan Liu [this message]
2016-03-14 7:54 ` Tetsuya Mukawa
2016-03-14 8:21 ` Yuanhan Liu
2016-03-14 8:31 ` Tetsuya Mukawa
2016-03-14 8:53 ` [dpdk-dev] [PATCH v3] " Tetsuya Mukawa
2016-03-14 9:12 ` Yuanhan Liu
2016-03-14 23:19 ` Thomas Monjalon
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