From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.forwardemail.net (smtp.forwardemail.net [121.127.44.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B57FF3BE629 for ; Tue, 26 May 2026 13:59:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=121.127.44.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779803981; cv=none; b=q/GYQEmk/kAzeAixCenqHEW5CtG3i/LHvjXdOIq/+LPHhE844fKFuv/LJIY9O14wXoS3xKSAxZwP4KhXLc88wRbWZfL7XTqCMquKyp29l8kujGl3P2DOsaZXN22t0LIzbyEDTExJ6R9cqSRCT5LlyaCov2zp29Tlpdpxa/8CoYg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779803981; c=relaxed/simple; bh=DaLbFcI+lM/MrKE6a75OHPZHts0DYRg5QLcbLfyB5us=; h=Mime-Version:Content-Type:Date:Message-Id:Subject:From:To; b=nd8sn9wr18wnAsO27i5ycBRHzsEHwNWT4kasSU8dCzRMvDjq5S+Ugv7VA8qFupoAbBD7L9HpAu4oGusaLN5Qnq2H6DS/9UFI0tNdZjERZaqRvW/S6xZ8UZRxcAFf3lntL6tjPP5QtlUD28gEhX+NnozjZcfZodchugQYoc+2HtU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ubuntu.com; spf=pass smtp.mailfrom=fe-bounces.ubuntu.com; dkim=pass (2048-bit key) header.d=ubuntu.com header.i=@ubuntu.com header.b=RKmV4oXw; arc=none smtp.client-ip=121.127.44.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ubuntu.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fe-bounces.ubuntu.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ubuntu.com header.i=@ubuntu.com header.b="RKmV4oXw" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ubuntu.com; h=To: From: Subject: Message-Id: Date: Content-Type: Content-Transfer-Encoding: Mime-Version; q=dns/txt; s=fe-953a8a3ca9; t=1779803973; bh=DaLbFcI+lM/MrKE6a75OHPZHts0DYRg5QLcbLfyB5us=; b=RKmV4oXw2p0BImdB+Fwro0TEXPq/xipz4HL0x8D8zQEJLKcr0CSf+KsfBft0Vr4tcHenjSk0R q8L3N/tj3aPU6GsU1MrWNXS4SYbewL7E7FmOtYnKEVPM9i+WI6SYzFKtidDFvnOG4T8Rl6Uwilp a2R4yAaEFS3WwtyYD7b7oc5rTQm4/Qbpscmc1e+SHHch3kS+NboHrSymnEvrEuQgalENMbNOU8f Ha3JgtDRJH0kebfNwxUlUaCKMB6x1EK+joEoluAsDee4Xt+qJwBfYXU7WdEdqwJeT2Cl8ID/2hg u3HFtZ3VKLnjF9D/SH8qSgOM+Wob7tDmQ+dCtFVoWfFw== X-Forward-Email-ID: 6a15a74331a45b28bf87669e X-Forward-Email-Sender: rfc822; jpeisach@ubuntu.com, smtp.forwardemail.net, 121.127.44.66 X-Forward-Email-Version: 2.8.15 X-Forward-Email-Website: https://forwardemail.net X-Complaints-To: abuse@forwardemail.net X-Report-Abuse: abuse@forwardemail.net X-Report-Abuse-To: abuse@forwardemail.net Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8; format=Flowed Date: Tue, 26 May 2026 09:59:30 -0400 Message-Id: Subject: [RFC] Timekeeping for other planets From: "Joshua Peisach" To: , "John Stultz" , "Thomas Gleixner" , "Stephen Boyd" , X-Mailer: aerc 0.21.0 Hi all, For a while I've thought about timekeeping on other planets. If humans ever make it to other planets, there will likely be other systems for keeping track of time, because the length of a day is not the same across all planets. Mars, for example, has a longer day than Earth. There are some proposed systems for timekeeping on Mars, the most interesting one being the Darian calendar system[1], but there are things like "Mars Sol Date" and Coordinated Mars Time (MTC). So my internal, curious and enthusiastic personality lead me to try making a C library that would try to handle time and date conversions for other planets. But it actually gets quite difficult and confusing, because (to save you the time and story) there ends up being "so what is an Earth second and what is a Mars second"? Now that I've made some kernel contributions (I still consider myself a newbie), I think about how there may actually be good reasons for trying to handle non-Earth times in the kernel, compared to the silly people like me having their timekeeping systems in userspace. For example, things like log timestamps. A machine that is running Linux on another planet (I know, it's ambitious, but humor me), will report events in terms of seconds. But, that's in terms of Earth seconds. For humans, it would make sense to use a time system that applies to Mars for its own calendars. So if someone is reading the logs and they see "one million seconds", how would they know exactly when the message occurred? One million Earth seconds does not equate to one million Mars seconds. (I try not to think about the "how long is a second" thing..) My point is, if humans adopt timekeeping systems for other planets, there may (or may not?) be a good reason for the kernel to keep track of time outside of Earth. Now, I am being ambitious, very optimistic, and potentially delusional for thinking that people would want to use other timekeeping systems in other planets, and still have Linux be around in the far future, and choose to have timekeeping in the kernel instead of in userspace. But, I know I'm not the only person interested in this topic. There is NASA's Mars24 Sunclock[2] which does track time in terms of hours, minutes and seconds, but at the rate that it does on Mars. So, the problem: There is currently no way to handle or provide timekeeping on other planets, aside from conversions. But maybe that should only stay in userspace. The users affected: well, as of writing, astronomers and space enthusiasts, looking to track events and time using other planetary timekeeping systems and calendars. I admittedly don't know much about timekeeping in the kernel, but there are functions for atomic time, which could actually get some use! Anyways, I thought I'd share this idea and ask for opinions. I think it's a fun idea. [1]: https://en.wikipedia.org/wiki/Timekeeping_on_Mars [2]: https://www.giss.nasa.gov/tools/mars24/ -Josh