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[77.37.180.76]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-55cef3cca16sm1836117e87.92.2025.08.18.13.54.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Aug 2025 13:54:23 -0700 (PDT) Date: Mon, 18 Aug 2025 23:54:20 +0300 From: Vadim Goncharov To: John Baldwin Cc: Konstantin Belousov , arch@freebsd.org Subject: Re: ABI guarantees Message-ID: <20250818235420.0d245ef1@nuclight.lan> In-Reply-To: <2fce0bfb-9ce7-40ce-8a27-f0103f531ca0@FreeBSD.org> References: <2fce0bfb-9ce7-40ce-8a27-f0103f531ca0@FreeBSD.org> X-Mailer: Claws Mail 3.21.0 (GTK+ 2.24.33; amd64-portbld-freebsd13.4) 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-Transfer-Encoding: 7bit X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Queue-Id: 4c5Q1z305jz3gbF On Mon, 18 Aug 2025 14:42:49 -0400 John Baldwin wrote: > Another gaping hole we have is sysctl(). We have no versioning of the ABI > expected by callers. Statically assigned MIBs can deal with this by bumping > the constant for the MIB, but most MIBs use OID_AUTO and sysctlbyname() > both of which bypass that. Would changing binary structures to some standard format e.g. CBOR (think it like binary JSON) or even ng_parse() ASCII format (or teach ng_parse() doing CBOR) help to alleviate the problem? ng_parse() allows to define many C structures by mechanical sed to macros. > For userspace I do think we want a higher bar, but I'm not sure that a bar > of "no binary can ever stop working" is fully feasible. The Secure RPC > case is an example where we've removed the necessary crypto bits because > they are insecure and deprecated. I would probably rather have stubs > for the libc symbols that fail immediately rather than keeping around the > implementation in the Secure RPC case. That might depend on your definition > of stability. Are stub symbols that permit an executable to still load > and execute but encounter errors if using the stubs considered an ABI > compat shim or ABI breakage? What about cases where we can't support > the old semantics? In 14.0 (I think) I removed kernel support for several > insecure crpyto algorithms that are formally deprecated for IPsec, and > we no longer support configuring them via setkey(8) or the like. The > binaries still work, but they will get an error back from the system call > if they use a deprecated algorithm. Is that ABI breakage? Don't know about IPsec but deleting blowfish was surely a mistake - it is not broken and could be used e.g. in IoT where space constraints matter, for those who know what they are doing. -- WBR, @nuclight