From nobody Thu Aug 24 16:19:51 2023 X-Original-To: dev-commits-src-all@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 4RWpFk2kgFz4rKvc; Thu, 24 Aug 2023 16:19:54 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (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 (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4RWpFk2BDBz4QhN; Thu, 24 Aug 2023 16:19:54 +0000 (UTC) (envelope-from jhb@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1692893994; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2wKn5xtzYQwTFv4RpIM7aOg2zfY/npjxvkMzOjHfX+c=; b=l0P1mAQol8dDp3NyYG7s6mgACTwBwyUCiFBy+KQ+UqXYsJYNJLrWphjZ7jZZh6cMJj907g LWWbColIcHddCIjN5++lzYoj+/D0MZ1KAikrGJwRLtICU7OqpV+phvsshYoa4vta6yuKTk 9QXy0XMtzSV2WGPcn6hoEF6bTImZWSR2YATqYHuTgmkWZLi8iC0VbysoZ8oVVG6DDRnA3f 8EVjjH/mGWjIrhaGKQUF5Sv2xPQmx6vLW87if7CD3DX+bjlIpSe6PZBv0cPxKZ0itpUXSX HUK0luqzK7fJSEtFldFS33NMnSnVDim4gLGdkt45J/BrsDO7qat6OTqvrdbziA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1692893994; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2wKn5xtzYQwTFv4RpIM7aOg2zfY/npjxvkMzOjHfX+c=; b=U0vOnF2iBKHTXZL7Wrj1JZPf1k2DC0hnqVKOHNuoa7e9AwSR+YHtpW9GkOdHbwudJMTPap xRF/86njcojeWOp2XycUE5Q/V9fq1ogWKe/wvxe2AWKz+EjkqVld7bjrssDwQfJMWztOhQ xmgKB5F8KkRAGW3+qVBX2Cw/Hs2gE5QNydltkqjgrhj8oWZKPjVHwxG8TaijUmUUt7Ykwc AgsYfVas9jWv+m3jjwrUeCMDGY1Oelg4D4PYgYD/vK1c8dC+ahL0SKRxsOTBdLLK8Q/hiR h//PikKz871YovVjtIkFIsrP0gI1taHIec+hxOvCdnGMfDX/j3S4qufhYJM1VA== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1692893994; a=rsa-sha256; cv=none; b=ZSVGmJcOiWiDgABjwVmVgSbksSnsLepwWl0nnfDZZ0T4OUbx6/LrVuumCo04CK20/vHgAv RVO0IinE4TCAIkOSRTzMSYYPNBhZo6gVV3hfRMEM6a8V2Zqv5tXxQos7mLppLdOSFcbVeM aK0t1TnQ4CwDoKHqomMvkLdzimrnsdzjWt5tvll4WIeufStsrQTO39ZE7vXI2yO9p3dQPg XjxDAZO6AC7YBO32tOTyybqJCD7mg9waQ5uBHkv6EJxqIMhMTU8p7x4ZatGpKejH8/wZbr h2BB3jV4bQULXw3drilOIDzScheiUJFOsE6Gb96F50h/Y6ZhAZrLT3sjf/UQkw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none Received: from [IPV6:2601:648:8683:a9e0:f5a2:610:c984:621d] (unknown [IPv6:2601:648:8683:a9e0:f5a2:610:c984:621d]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 4RWpFj3lBRz12lm; Thu, 24 Aug 2023 16:19:53 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Message-ID: <747e34d5-8191-5fb9-deb4-c94d7f1693e0@FreeBSD.org> Date: Thu, 24 Aug 2023 09:19:51 -0700 List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: git: 4a69fc16a583 - main - Add membarrier(2) Content-Language: en-US To: Warner Losh , Jessica Clarke Cc: Konstantin Belousov , "src-committers@freebsd.org" , "dev-commits-src-all@freebsd.org" , "dev-commits-src-main@freebsd.org" References: <202308230007.37N07cOK082906@gitrepo.freebsd.org> <748B7A01-5011-44EE-BB04-282AE96F9B5B@freebsd.org> <0F3EA94D-6696-471C-ABF6-840B5E92967F@freebsd.org> From: John Baldwin In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/23/23 6:01 AM, Warner Losh wrote: > On Tue, Aug 22, 2023 at 11:37 PM Jessica Clarke wrote: > >> >>> The addition does not change any existing code path in the kernel. >> >> No, but it commits us to a new syscall being stable just days before 14 >> branches and has its ABI frozen. >> > > I'd planned on committing timerfd later today. I didn't consider it an ABI > breakage, since it was just additive. It's one of the things that can be > MFC'd (we don't prohibit new system calls). (Not taking a side on the merits of the current membarrier(2) implementation) I think Jess's point here is not that a new syscall is not a valid ABI breakage, but more that once you add a new syscall that makes it into a release, now the ABI of that syscall is frozen and can't be changed. That said, syscall numbers are relatively "cheap", so if we had to renumber membarrier(2) because its ABI was found to be a problem that could be done, albeit at the cost of keeping the old one around under COMPAT_FREEBSD. -- John Baldwin