From nobody Mon Nov 20 17:54:22 2023 X-Original-To: freebsd-current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4SYwBH3Nrkz51d39 for ; Mon, 20 Nov 2023 17:54:31 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (www.zefox.net [50.1.20.27]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "www.zefox.com", Issuer "www.zefox.com" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4SYwBH0JV5z3FC9; Mon, 20 Nov 2023 17:54:30 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Authentication-Results: mx1.freebsd.org; none Received: from www.zefox.net (localhost [127.0.0.1]) by www.zefox.net (8.17.1/8.15.2) with ESMTPS id 3AKHsNlX027126 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 20 Nov 2023 09:54:23 -0800 (PST) (envelope-from fbsd@www.zefox.net) Received: (from fbsd@localhost) by www.zefox.net (8.17.1/8.15.2/Submit) id 3AKHsNpG027125; Mon, 20 Nov 2023 09:54:23 -0800 (PST) (envelope-from fbsd) Date: Mon, 20 Nov 2023 09:54:22 -0800 From: bob prohaska To: Zhenlei Huang Cc: freebsd-current@freebsd.org Subject: Re: How much survives an install/reboot cycle? Message-ID: References: List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spamd-Bar: ---- X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:7065, ipnet:50.1.16.0/20, country:US] X-Rspamd-Queue-Id: 4SYwBH0JV5z3FC9 On Mon, Nov 20, 2023 at 09:12:45AM +0800, Zhenlei Huang wrote: > > > > On Nov 19, 2023, at 11:51 PM, bob prohaska wrote: > > > > How much of a running system's state survives a reboot? I used to think > > the answer was "nothing", but from time to time a second reboot behaves > > a little differently from the previous one. > > Warner has a good description about that. I totally agree. > > > > > The most recent example was an update to bpf.c: Prior to the update an > > armv7 system had been inclined to drop ssh connections left up for days. > > After updating and running a build/install cycle the behavior persisted, > > but since a second reboot with no intentional changes it has stopped. > > The most recent change to bpf.c is 7a974a649848 (bpf: Make dead_bpf_if const) . > It is not a functional change, and I do not think it will affect ssh. > There could be issues under the earth. > That is most helpful. Very likely the change I saw is simply coincidence. > Anyway please do not hesitate to report if you get recovered by reverting 7a974a649848. In this case I don't want to revert, the new behavior is desirable. My only puzzle was the seeming delay in its appearance. The only consistent issue remaining is reported in Bug 273566 . It finally dawned on me that the garbage characters must be originated on the USB end, transmitted to the getty process watching the serial end and get stuck in the transmit buffer when the link goes down. When the serial link comes back up they appear on the receiving console display. Many thanks to you and Warner! bob prohaska