From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF980243387 for ; Mon, 4 Aug 2025 09:07:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754298481; cv=none; b=HBqgc+iEnQ4Sz5sM7uQWiQI+VUDypQljr3b6pQBK27QifxrtAjta+MZbpUu+ySOWFJccrGYao9QpbDy1aWcBLdMVu+lMBMoX3AyH2ddQWerYnGfd/oOog879SzccbP3on4F5EW7YRfkfPdyOdVaebF44GkzgNTDwDsCq7R8aqOY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754298481; c=relaxed/simple; bh=cl/NxNnFX0+amow2/BlxvTWfRiEca6TibWdiIVHZNN8=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=hqq0RcQxCzmqX23jsJpOyhDjqruMiv0YQhdoSm5G9BKqSiono+uz6bYsg1iKYmVQSM7WHMj6up6QoPmId6EmrUSxchx+PHQ0Oz1faVHQfl50ww5CYFs12dJ1NjBsMys3SiySgnZX6qI3WDA61B2Q+b7bW2u4U9d/F3I+Ls4TpYE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=casper.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=raTaQQHG; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=casper.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="raTaQQHG" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=cl/NxNnFX0+amow2/BlxvTWfRiEca6TibWdiIVHZNN8=; b=raTaQQHG7JiXzoQ+iaSqaHwz5z 8sHivqd23IXb+udhezpUsXppH/8qfCEUHWjiAqimI61LPWlYtUt72RxjyegRS+m+UPkj222TTiD27 yUK2fOyAHCr1qV5kPp2vURHmE+VUVF3m67E0ctaNTVmKcoIfJTglgvUHaNGHvZSIRnqDJ0moMRJah mNGCkNahFrq9f+UsS5qTQO4vLrqj/o2f4bK/zmUmelRbJoZKWRSez7MQe728jJss/VvNz5U+MfUSk 46iGJnZKzko7N0A49DVDJ2LFI13g0gZKDIXjqnEMJn6HANXlEN/mUXwIi/+beG9WiMgAXhnyBS79d vYFL34LA==; Received: from 54-240-197-234.amazon.com ([54.240.197.234] helo=u09cd745991455d.ant.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uirAb-0000000Db7B-0v3i; Mon, 04 Aug 2025 09:07:50 +0000 Message-ID: Subject: Re: [RFC PATCH net-next] ptp: Introduce PTP_SYS_OFFSET_EXTENDED_TRUSTED ioctl From: David Woodhouse To: Julien Ridoux , mlichvar@redhat.com Cc: akiyano@amazon.com, aliguori@amazon.com, alisaidi@amazon.com, amitbern@amazon.com, andrew@lunn.ch, benh@amazon.com, darinzon@amazon.com, davem@davemloft.net, dwmw@amazon.com, edumazet@google.com, evgenys@amazon.com, evostrov@amazon.com, joshlev@amazon.com, kuba@kernel.org, matua@amazon.com, msw@amazon.com, nafea@amazon.com, ndagan@amazon.com, netanel@amazon.com, netdev@vger.kernel.org, ofirt@amazon.com, pabeni@redhat.com, richardcochran@gmail.com, ridouxj@amazon.com, saeedb@amazon.com, tglx@linutronix.de, zorik@amazon.com Date: Mon, 04 Aug 2025 10:07:48 +0100 In-Reply-To: <20250803235142.57900-1-julien@synclab.org> References: <20250803235142.57900-1-julien@synclab.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-Iph05W811DZgyBjyIvGb" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html --=-Iph05W811DZgyBjyIvGb Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, 2025-08-03 at 16:51 -0700, Julien Ridoux wrote: > > On 7/28/25, 7:28 AM, "Miroslav Lichvar" > > > wrote: > >=20 > > On Thu, Jul 24, 2025 at 02:56:56PM +0300, David Arinzon wrote: > > > The proposed PTP_SYS_OFFSET_EXTENDED_TRUSTED ioctl offers the > > > same timestamps as the PTP_SYS_OFFSET_EXTENDED ioctl, but extends > > > it with a measurement of the PHC device clock accuracy and the > > > synchronization status. This supports two objectives. > >=20 > >=20 > > I have a slight issue with the naming of this new ioctl. TRUSTED > > implies to me the other supported ioctls are not to be trusted > > for some reason, but that's not the case, right? It's just more > > information provided, i.e. it's extended once again. Would > > PTP_SYS_OFFSET_EXTENDED3 or PTP_SYS_OFFSET_EXTENDED_ATTRS not work > > better? >=20 > That's a fair call. The ioctl can be renamed to > PTP_SYS_OFFSET_EXTENDED_ATTRS While we're talking about extending the userspace API... I think I'd also like a way to use the actual hardware counter (TSC, arch timer) as the reference clockid instead of CLOCK_MONOTONIC etc.=20 In a hosting environment, I barely even care about calibrating the host kernel's timekeeping against the external time reference. What I *do* care about calibrating is the hardware counter, so that it can be correctly advertised to guests through a vmclock device. Using vmclock and simply advertising the relationship between the hardware counter and precision time, makes *so* much more sense than having hundreds of virtual guests on the same machine all performing the *same* calibration of precisely the same underlying counter, each of them potentially experiencing latency of measurements due to steal time while they do so. --=-Iph05W811DZgyBjyIvGb Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv 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