From owner-freebsd-hackers@freebsd.org Wed Aug 1 15:28:58 2018 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9064C10608D6 for ; Wed, 1 Aug 2018 15:28:58 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: from mail-pl0-x242.google.com (mail-pl0-x242.google.com [IPv6:2607:f8b0:400e:c01::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 157F57955E for ; Wed, 1 Aug 2018 15:28:58 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: by mail-pl0-x242.google.com with SMTP id j8-v6so8964494pll.12 for ; Wed, 01 Aug 2018 08:28:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=z4cR5fWOp3fzlJ4njMceI+rO4svDitf877Y/INlyz4M=; b=gsy2UyUkdE+uySsprmC36VjXrUZNpn2E9wFTscrqf00UmIgxkRHkNhP8CknWDQtrjL z68aKeKRqwRXzkc8ZZx1Zyt9XDva1LNFWUMFnxNfvGsGD7QKwpEpB0Vth8P2nNsVspb2 8tQgEtjD2X61pjkvqRG8mKV1h7vrYYAZ054r2qxrxVSHPN/jehfvHDAUKi8bFpfI75Zm YVP1zK+WhggStlmknZwBhjTMAuXJQnwd9TFLH4YXgVJYUksrXMpq52IwILXOtShOCz5n 9gPq7dTaziHPcN2UB7cHPqiinebIi/NJAQZYzwdNGTfWYF9784ytjjMELjOnz05HUfzS thFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=z4cR5fWOp3fzlJ4njMceI+rO4svDitf877Y/INlyz4M=; b=MVkh2OBa7xD+fsguAicVP9aGHX+Y8lSmqKUYWG6pDYew6egRWJdD9bNUXGvXIAgTx6 ZXQy8syQ89b+XCviNyImT6mDKcyHTxI+WEzS0SpJmSvDvQ9sElX9ty8xyeGRcraQGLga brTa1InHBzjp7OhL8wA9hgW9Ld0a5023SEWK7+mEww4EgVqAr6aWgP/mY712NMbA1kPM haJIH3hF2RTUrRoc7ZLWju8eoA2+99CNUTXP7uHEEJWIf/6/I7mp/1tbn4aPCrjF2sIi aLjirYfdCLmTM6E2yYbkwgaFIG9aELewk0eR0Vo5T9Z/vmDTtCytUVt9J8Lrs7a8WQ6z Ieog== X-Gm-Message-State: AOUpUlEt/cczOyRX7W0F2wGipkUzTSN0GhWkpniY5KHcquvA4xGRm54J i9E2n5O9kYzZDra5hkJhIabuNcW/ X-Google-Smtp-Source: AAOMgpf8uiTywjpB8mwF97ANMu7OSYJArXcpqqhmY3wdxfQym9vy4XGcr/D4KTaJnV4kWjC23WmZbA== X-Received: by 2002:a17:902:9695:: with SMTP id n21-v6mr25242331plp.6.1533137337204; Wed, 01 Aug 2018 08:28:57 -0700 (PDT) Received: from raichu (toroon0560w-lp130-09-70-52-224-239.dsl.bell.ca. [70.52.224.239]) by smtp.gmail.com with ESMTPSA id d13-v6sm18726741pgq.42.2018.08.01.08.28.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 01 Aug 2018 08:28:56 -0700 (PDT) Sender: Mark Johnston Date: Wed, 1 Aug 2018 11:28:53 -0400 From: Mark Johnston To: Konstantin Belousov Cc: freebsd-hackers@freebsd.org Subject: Re: COMPAT_43 users? Message-ID: <20180801152853.GC97237@raichu> References: <20180731214920.GA95743@raichu> <20180801075512.GR40119@kib.kiev.ua> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180801075512.GR40119@kib.kiev.ua> User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Aug 2018 15:28:58 -0000 On Wed, Aug 01, 2018 at 10:55:12AM +0300, Konstantin Belousov wrote: > On Tue, Jul 31, 2018 at 05:49:20PM -0400, Mark Johnston wrote: > > The COMPAT_43 kernel option, which enables syscall support for 4.3BSD > > binaries, hasn't been enabled in the standard kernel configs for well > > over a decade, and doesn't appear to be a dependency of any other kernel > > features. Nonetheless, the kernel contains quite a bit of code to > > support this option. Does anyone use it in modern versions of FreeBSD > > or have any arguments for keeping it? > > COMPAT_43 means two things, the third part is a.out image activator. > First thing is the lcall $7.$0 syscall emulator, both on amd64 and > (surprisingly) i386, after 4/4 split. Second thing is the syscalls > compat shims. > > Together, all three things allow to run pre-3.x binaries on the modern > machines, including amd64. I think this is useful at least for 'waving > the flag' about our ABI compatibility guarantees, and for the historic > software reconstruction. I run 1.1.8 chroot and several old binaries > sometimes, I know that bde does, and there was at least one more user > some time ago. > > What do you mean by a lot of code ? Syscall compats is relatively easy. > lcall $7,$0 emulation is very non-trivial but tiny. I do maintain this > code and do not want it to go away. Thanks, fair enough. The question was prompted by seeing lots of COMPAT_OLDSOCK ifdefs while working on some socket code.