From: "Michael S. Tsirkin" <mst@redhat.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Richard Cochran <richardcochran@gmail.com>,
Peter Hilber <peter.hilber@opensynergy.com>,
linux-kernel@vger.kernel.org, virtualization@lists.linux.dev,
linux-arm-kernel@lists.infradead.org, linux-rtc@vger.kernel.org,
"Ridoux, Julien" <ridouxj@amazon.com>,
virtio-dev@lists.linux.dev, "Luu, Ryan" <rluu@amazon.com>,
"Chashper, David" <chashper@amazon.com>,
"Mohamed Abuelfotoh, Hazem" <abuehaze@amazon.com>,
"Christopher S . Hall" <christopher.s.hall@intel.com>,
Jason Wang <jasowang@redhat.com>,
John Stultz <jstultz@google.com>,
netdev@vger.kernel.org, Stephen Boyd <sboyd@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Alessandro Zummo <a.zummo@towertech.it>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
qemu-devel <qemu-devel@nongnu.org>,
Simon Horman <horms@kernel.org>
Subject: Re: [PATCH] ptp: Add vDSO-style vmclock support
Date: Fri, 26 Jul 2024 08:47:13 -0400 [thread overview]
Message-ID: <20240726084424-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <f2e85f8f568f8a21b2178e59d8387d7a52a843bd.camel@infradead.org>
On Fri, Jul 26, 2024 at 09:06:29AM +0100, David Woodhouse wrote:
> That's great. You don't even need it to be per-vCPU if you let the
> hypervisor write directly to the single physical location that's mapped
> to userspace. It can do that before it even starts *running* the vCPUs
> after migration. It's a whole lot simpler.
It *seems* simpler, until you realize that there is no way
to change anything in the interface, there is no negotiation
between hypervisor and userspace. If I learned anything at all
in tens of years working on software, it's that it is
never done. So let's have userspace talk to the kernel
and have kernel talk to the devices, please. There's
no compelling reason to have this bypass here.
--
MST
next prev parent reply other threads:[~2024-07-26 12:47 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-24 17:16 [PATCH] ptp: Add vDSO-style vmclock support David Woodhouse
2024-07-25 5:48 ` Michael S. Tsirkin
2024-07-25 9:56 ` David Woodhouse
2024-07-25 11:31 ` Daniel P. Berrangé
2024-07-25 11:53 ` David Woodhouse
2024-07-25 12:00 ` Daniel P. Berrangé
2024-07-25 12:17 ` Michael S. Tsirkin
2024-07-25 12:27 ` David Woodhouse
2024-07-25 12:29 ` Michael S. Tsirkin
2024-07-25 12:31 ` David Woodhouse
2024-07-25 12:33 ` Michael S. Tsirkin
2024-07-25 13:50 ` David Woodhouse
2024-07-25 14:11 ` Michael S. Tsirkin
2024-07-25 15:18 ` David Woodhouse
2024-07-25 16:38 ` Michael S. Tsirkin
2024-07-25 19:35 ` David Woodhouse
2024-07-25 20:50 ` Michael S. Tsirkin
2024-07-25 21:00 ` David Woodhouse
2024-07-25 21:04 ` Michael S. Tsirkin
2024-07-25 21:29 ` David Woodhouse
2024-07-25 21:47 ` Michael S. Tsirkin
2024-07-25 22:20 ` David Woodhouse
2024-07-26 6:06 ` Michael S. Tsirkin
2024-07-26 8:35 ` David Woodhouse
2024-07-26 12:52 ` Michael S. Tsirkin
2024-07-26 13:00 ` David Woodhouse
2024-07-26 13:04 ` Michael S. Tsirkin
2024-07-26 13:08 ` David Woodhouse
2024-07-26 5:09 ` Michael S. Tsirkin
2024-07-26 5:55 ` Michael S. Tsirkin
2024-07-26 8:06 ` David Woodhouse
2024-07-26 12:47 ` Michael S. Tsirkin [this message]
2024-07-26 12:51 ` David Woodhouse
2024-07-26 16:49 ` Jonathan Cameron via
2024-07-26 18:28 ` David Woodhouse
2024-07-28 10:37 ` Michael S. Tsirkin
2024-07-28 13:07 ` David Woodhouse
2024-07-28 15:23 ` Michael S. Tsirkin
2024-07-29 6:45 ` David Woodhouse
2024-07-25 5:54 ` Michael S. Tsirkin
2024-07-25 10:00 ` David Woodhouse
2024-07-25 11:20 ` Paolo Abeni
2024-07-25 11:49 ` David Woodhouse
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