From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 10317 invoked from network); 24 Dec 2021 03:49:14 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 24 Dec 2021 03:49:14 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 7505A9CEB2; Fri, 24 Dec 2021 13:49:12 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id DAF029CC17; Fri, 24 Dec 2021 13:48:45 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 415B69CC17; Fri, 24 Dec 2021 13:48:42 +1000 (AEST) Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by minnie.tuhs.org (Postfix) with ESMTPS id 7DCD29CC01 for ; Fri, 24 Dec 2021 13:48:38 +1000 (AEST) Received: from cwcc.thunk.org (pool-108-7-220-252.bstnma.fios.verizon.net [108.7.220.252]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 1BO3mUpg017071 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 23 Dec 2021 22:48:32 -0500 Received: by cwcc.thunk.org (Postfix, from userid 15806) id C40C815C00C8; Thu, 23 Dec 2021 22:48:30 -0500 (EST) Date: Thu, 23 Dec 2021 22:48:30 -0500 From: "Theodore Ts'o" To: Steve Nickolas Message-ID: References: <818A6F70-D117-471A-9E08-E37B34F8FAE0@mac.com> <20211223021805.GK24180@mcvoy.com> <20211223141958.GR24180@mcvoy.com> <20211223161923.GT24180@mcvoy.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [TUHS] Photos of University Computer Labs - now off topic X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On Thu, Dec 23, 2021 at 05:13:39PM -0500, Steve Nickolas wrote: > On Thu, 23 Dec 2021, Larry McVoy wrote: > > > On Thu, Dec 23, 2021 at 10:02:40AM -0600, Warner Losh wrote: > > > > I had forgotten about control-t - does anything modern still do that > > > > > > FreeBSD does. It's my biggest annoyance with Linux that it doesn't. > > > > Seems like a patch might be nice. > > Yeah, I miss SIGINFO when I'm on Linux. There have been patches proposed, but it turns out the sticky wicket is that we're out of signal numbers on most architectures. There are code points that potentially could be repurposed, since they aren't actually signaled from the kernel: SIGLOST - Term File lock lost (unused) SIGSTKFLT - Term Stack fault on coprocessor (unused) Howveer, the current behavior if no signal handler is installed is to terminate the process --- and it's unclear whether there might be some user space libraries that might be using these signals for their own nefarious purposes. So someone would have to deprecate one of these signals, and then try to do a code search across the internet to see if there's any evidence that SIGLOST or SIGSTKFLT is being used (at least in open source software). It's not impossible to deal with this, but no one has cared enough to really try to push this through as a new feature. Cheers, - Ted