From: Ross Lagerwall <ross.lagerwall@citrix.com>
To: Tu Dinh <ngoc-tu.dinh@vates.tech>, xen-devel@lists.xenproject.org
Cc: "Paul Durrant" <paul@xen.org>, "Jan Beulich" <jbeulich@suse.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Roger Pau Monné" <roger@xenproject.org>,
"Teddy Astie" <teddy.astie@vates.tech>
Subject: Re: [PATCH v1 2/2] x86/viridian: Implement synthetic timer direct mode
Date: Fri, 28 Aug 2026 15:17:46 +0100 [thread overview]
Message-ID: <dbfca751-4bd0-46f1-824b-43a9856031b0@citrix.com> (raw)
In-Reply-To: <1787926292.8631fc262581453bbf619ec5b2062170.1a048b62786000c4f3@vates.tech>
On 8/28/26 3:11 PM, Tu Dinh wrote:
> On 28/08/2026 15:14, Ross Lagerwall wrote:
>> In direct mode, the timer asserts an interrupt on expiration rather than
>> using a SynIC message. It is useful to implement this since Windows 11's
>> Hyper-V can only use synthetic timers in direct mode.
>
> Hello, is this new behavior compared to Server 2025? What happens if
> direct mode is not available, does it fall back to disabling stimer?
No, it's not new behaviour. According to Linux commit 8644f771e07c it
has been this way since 2016. If direct mode is not available, the VM
still works but without using synthetic timers.
Ross
prev parent reply other threads:[~2026-08-28 14:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 13:11 [PATCH v1 0/2] Viridian changes for Hyper-V as a guest Ross Lagerwall
2026-08-28 13:11 ` [PATCH v1 1/2] x86/viridian: Workaround Hyper-V GP fault writing to MSR Ross Lagerwall
2026-08-28 13:11 ` [PATCH v1 2/2] x86/viridian: Implement synthetic timer direct mode Ross Lagerwall
2026-08-28 14:11 ` Tu Dinh
2026-08-28 14:17 ` Ross Lagerwall [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=dbfca751-4bd0-46f1-824b-43a9856031b0@citrix.com \
--to=ross.lagerwall@citrix.com \
--cc=andrew.cooper3@citrix.com \
--cc=jbeulich@suse.com \
--cc=ngoc-tu.dinh@vates.tech \
--cc=paul@xen.org \
--cc=roger@xenproject.org \
--cc=teddy.astie@vates.tech \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.