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From: Arnd Bergmann <arnd@kernel.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Jason Wang" <jasowang@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
	"Vincent Guittot" <vincent.guittot@linaro.org>,
	"Jean-Philippe Brucker" <jean-philippe@linaro.org>,
	"Bill Mills" <bill.mills@linaro.org>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Enrico Weigelt, metux IT consult" <info@metux.net>,
	virtio-dev@lists.oasis-open.org,
	"Geert Uytterhoeven" <geert@linux-m68k.org>
Subject: Re: [virtio-dev] Re: [PATCH V5 2/2] virtio-gpio: Add support for interrupts
Date: Tue, 20 Jul 2021 09:22:31 +0200	[thread overview]
Message-ID: <CAK8P3a0DbdoJcsxxDX9OgvtmKPhpuYic4FaDUVzDJNFmaWWJsA@mail.gmail.com> (raw)
In-Reply-To: <20210720071149.inex3wzdgrwrvlgw@vireshk-i7>

On Tue, Jul 20, 2021 at 9:11 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 20-07-21, 09:01, Arnd Bergmann wrote:
> > That's what I was hoping for, I'm just not sure if this is required
> > by the virtio spec or just the usual implementation of the device
> > side. Have you found a section in the spec that guarantees that
> > the virtqueue_kick() serves as a sufficient barrier that the driver
> > can rely on the information having arrived?
>
> This is what the spec say about it:
>
> https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.html#x1-9000023

I don't see it spell out whether this acts as a barrier or not. As far
as I can tell, the notification may be deferred, e.g. if the host is
multi-threaded and virtqueue_kick() needs to send an IPI to another
processor to look at the data.

       Arnd


  reply	other threads:[~2021-07-20  7:22 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16  7:39 [PATCH V5 0/2] virtio: Add specification for virtio-gpio Viresh Kumar
2021-07-16  7:39 ` [PATCH V5 1/2] virtio-gpio: Add the device specification Viresh Kumar
2021-07-16  8:23   ` Arnd Bergmann
2021-07-16 16:26     ` Viresh Kumar
2021-07-16 18:20       ` Arnd Bergmann
2021-07-19  9:29         ` Viresh Kumar
2021-07-19 10:40           ` [virtio-dev] " Arnd Bergmann
2021-07-19 10:50             ` Viresh Kumar
2021-07-19 11:48             ` Geert Uytterhoeven
2021-07-19  7:32       ` Viresh Kumar
2021-07-16  9:13   ` Geert Uytterhoeven
2021-07-16 15:43     ` Viresh Kumar
2021-07-16 15:22   ` Michael S. Tsirkin
2021-07-16 15:41     ` Viresh Kumar
2021-07-16  7:39 ` [virtio-dev] [PATCH V5 2/2] virtio-gpio: Add support for interrupts Viresh Kumar
2021-07-16  9:02   ` Arnd Bergmann
2021-07-16 15:17     ` [virtio-dev] " Viresh Kumar
2021-07-16 16:19       ` Arnd Bergmann
2021-07-16 16:50         ` Viresh Kumar
2021-07-16 18:49           ` Arnd Bergmann
2021-07-20  5:47             ` Viresh Kumar
2021-07-20  7:01               ` Arnd Bergmann
2021-07-20  7:11                 ` Viresh Kumar
2021-07-20  7:22                   ` Arnd Bergmann [this message]
2021-07-19 10:24   ` Viresh Kumar
2021-07-19 12:00     ` Arnd Bergmann
2021-07-20  6:11       ` Viresh Kumar
2021-07-20  7:17         ` Arnd Bergmann
2021-07-20  7:53           ` Viresh Kumar
2021-07-20  8:10             ` Arnd Bergmann
2021-07-20  8:42               ` Viresh Kumar
2021-07-20  9:50             ` Michael S. Tsirkin
2021-07-19 15:11     ` Michael S. Tsirkin
2021-07-20  4:19       ` Viresh Kumar
2021-07-16  9:57 ` [PATCH V5 0/2] virtio: Add specification for virtio-gpio Arnd Bergmann
2021-07-16 16:57   ` Viresh Kumar

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