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 170DE2C0285; Thu, 21 Aug 2025 20:12:57 +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=1755807179; cv=none; b=leEPL+BZDAVzuZ6tfYaINbRUgminCEv5JPH/V9HAfzeI4ZR7mKWUygTWaBcVtdIMGealYwEfwikDnabCH0DTMLrlwvpEJUoYjY/fEMTsCXnNzZYWMwajCcNzv7CaGlvqA960lTUJyn9Tf5tu5U1G4upKnIhGDdtaXkOy+SkqGjk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755807179; c=relaxed/simple; bh=Gt4kvNq3TwjewAaGjCsWVdpvg2PXkC+KlGQc3DaUCZk=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=cN1rOoIIf+0d2gy7xJ23qXKau1uBDNEETQVCRWpeqESXG0gnq3ZMRTFAbLhIVvxITpSVyUa6gIhVtmcbPlDFumnwh+Ez9ADb1ZNxLNOgBUpROH7dqlTJpGcU7ONbOBlGKiJp2yiW0yRTd3l94l1SFABxhclF5NNsydLPrQiPz4Y= 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=rWOf8Uyg; 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="rWOf8Uyg" 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=Gt4kvNq3TwjewAaGjCsWVdpvg2PXkC+KlGQc3DaUCZk=; b=rWOf8UygtYyyAHBCXVjz6q/zG7 FmSCkNFJlitNCxgQW4cOzlpX/7X7HiiT5R0Z5tVl3bDEe53R+UBWkoR7ZqJfUpioxiH2xbmO/5RW7 BxuRHpjn2o5Pam/deqbd+fL/v//PDrrdJCGGtHAn0p3FRLj5nSDgeLGSC/OcU3rufBnBhoEc3sNuK tA4bu2PUs7cRRZm0m//z/3K28+Lk0o9yM8vhHifaZ/JA4wbypBlRyDaJbY+F0TqJBnrB8967axUXM pI6djPQEz7Zy/sdJBvhghRyYNf6V39253xl78AKulI7Ikkr11Nkl5yxJSdZUZPJqJMcyRZiogxUOU ZFTsOdhA==; Received: from 54-240-197-225.amazon.com ([54.240.197.225] helo=freeip.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1upBeS-0000000D6F5-2pUw; Thu, 21 Aug 2025 20:12:49 +0000 Message-ID: <91008c3cd2502b3726992b0f490aac54a1efa186.camel@infradead.org> Subject: Re: [PATCH net-next v4] ptp: add Alibaba CIPU PTP clock driver From: David Woodhouse To: Richard Cochran , Jakub Kicinski Cc: Wen Gu , andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, xuanzhuo@linux.alibaba.com, dust.li@linux.alibaba.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner Date: Thu, 21 Aug 2025 21:12:48 +0100 In-Reply-To: References: <20250812115321.9179-1-guwen@linux.alibaba.com> <20250815113814.5e135318@kernel.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-CfPXHiyIKvjiTwFs/JVA" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: linux-kernel@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 --=-CfPXHiyIKvjiTwFs/JVA Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2025-08-21 at 13:05 -0700, Richard Cochran wrote: > On Fri, Aug 15, 2025 at 11:38:14AM -0700, Jakub Kicinski wrote: >=20 > > Maybe it's just me, but in general I really wish someone stepped up > > and created a separate subsystem for all these cloud / vm clocks. > > They have nothing to do with PTP. In my mind PTP clocks are simple HW > > tickers on which we build all the time related stuff. While this driver > > reports the base year for the epoch and leap second status via sysfs. >=20 > Yeah, that is my feeling as well. Agreed. While vmclock is presented as a PTP clock for compatibility, it's more than that because it can do better than simply giving a single precise point in time. It actually tells the guest the precise relationship between the hardware counter and real time, much like the private data structure exposed from the kernel to vDSO gettimeofday. We should work on having the kernel consume that *directly* and feed its CLOCK_REALTIME with it. Having hundreds of guests on the same host all recalculate the same thing based on a set of points in time, obtained through /dev/ptpX or otherwise, is just daft. --=-CfPXHiyIKvjiTwFs/JVA Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj jfhCFqxYyRiW8g3cNFAvltDbK5AzcOaR7yVzVGadr4YcCVxjKrEJOgi7WEOH8rUgCNB5cTD8N/Et GfZI+LGqSv0YtNa54T9D1AWJy08ZKkWvfGGIXN9UFAPMJ6OLLH/UUEgFa+7KlrEvMUupDFGnnR06 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