From nobody Fri Dec 2 00:33:00 2022 X-Original-To: freebsd-arch@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 4NNYns2J6kz4jp8J for ; Fri, 2 Dec 2022 00:33:21 +0000 (UTC) (envelope-from ehem@m5p.com) Received: from mailhost.m5p.com (mailhost.m5p.com [74.104.188.4]) (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 "m5p.com", Issuer "R3" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4NNYnr465kz41Lv for ; Fri, 2 Dec 2022 00:33:20 +0000 (UTC) (envelope-from ehem@m5p.com) Authentication-Results: mx1.freebsd.org; dkim=none; spf=pass (mx1.freebsd.org: domain of ehem@m5p.com designates 74.104.188.4 as permitted sender) smtp.mailfrom=ehem@m5p.com; dmarc=none Received: from m5p.com (mailhost.m5p.com [IPv6:2001:470:1f07:15ff:0:0:0:f7]) by mailhost.m5p.com (8.16.1/8.15.2) with ESMTPS id 2B20X1GB066339 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Thu, 1 Dec 2022 19:33:07 -0500 (EST) (envelope-from ehem@m5p.com) Received: (from ehem@localhost) by m5p.com (8.16.1/8.15.2/Submit) id 2B20X0cv066338; Thu, 1 Dec 2022 16:33:00 -0800 (PST) (envelope-from ehem) Date: Thu, 1 Dec 2022 16:33:00 -0800 From: Elliott Mitchell To: Warner Losh Cc: "freebsd-arch@freebsd.org" Subject: Re: Giant Locked drivers Message-ID: References: List-Id: Discussion related to FreeBSD architecture List-Archive: https://lists.freebsd.org/archives/freebsd-arch List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-arch@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=0.4 required=10.0 tests=KHOP_HELO_FCRDNS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on mattapan.m5p.com X-Spamd-Result: default: False [-3.26 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.96)[-0.962]; R_SPF_ALLOW(-0.20)[+a]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_TWO(0.00)[2]; MLMMJ_DEST(0.00)[freebsd-arch@freebsd.org]; TO_DN_EQ_ADDR_SOME(0.00)[]; R_DKIM_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_MATCH_FROMTLD(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; ASN(0.00)[asn:701, ipnet:74.104.0.0/16, country:US]; FROM_HAS_DN(0.00)[]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_SOME(0.00)[]; DMARC_NA(0.00)[m5p.com]; RCVD_TLS_LAST(0.00)[]; TAGGED_FROM(0.00)[freebsd] X-Rspamd-Queue-Id: 4NNYnr465kz41Lv X-Spamd-Bar: --- X-ThisMailContainsUnwantedMimeParts: N On Tue, Nov 15, 2022 at 10:37:36AM -0700, Warner Losh wrote: > When set to 0, you get today's behavior. If set to 1, it will no longer > allow drivers that don't request MPSAFE interrupt handlers from registering > (the interrupt setup will return an error). > > This will allow us to understand what is lost if we throw the switch, and > allow users to proactively test their systems to see if they are > affected or not (and if they are, if they want to live without the > functionality, or want to fund work in the area). > > Comments? Partially building on Ed Maste's idea; perhaps the value 1 should be allow giant-locked drivers and -1 should disallow giant-locked drivers. Then use 0 for interesting behavior. Perhaps a value of 0 should be switched to 1 90% of the time and -1 1% of the time. Theory being to be annoying enough to attact attention, but not annoying enough to be turned off. I'm at least partially joking, but it might be a way to cause progress (or might cause trouble). In other news in two handy VMs. On x86: (a full VM with hardware emulation) atkbd0: [GIANT-LOCKED] psm0: [GIANT-LOCKED] WARNING: Device "psm" is Giant locked and may be deleted before FreeBSD 14.0. On ARM64: (basically pure VM with no emulated hardware) So right now everyone is reporting x86 console devices and nothing else. This suggests the x86 console is urgent for giant removal. Then perhaps it will be viable to default to disabled (or perhaps something else will float to the top). -- (\___(\___(\______ --=> 8-) EHM <=-- ______/)___/)___/) \BS ( | ehem+sigmsg@m5p.com PGP 87145445 | ) / \_CS\ | _____ -O #include O- _____ | / _/ 8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445