From owner-freebsd-current@FreeBSD.ORG Wed Mar 18 19:28:08 2015 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id AD3393D7; Wed, 18 Mar 2015 19:28:08 +0000 (UTC) Received: from mail-ie0-x233.google.com (mail-ie0-x233.google.com [IPv6:2607:f8b0:4001:c03::233]) (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 6EFBCD2C; Wed, 18 Mar 2015 19:28:08 +0000 (UTC) Received: by ieclw3 with SMTP id lw3so47631233iec.2; Wed, 18 Mar 2015 12:28:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=LlrzV+9gtZomexC5Y288eoQ7RUB/sQleqQ21Z0veGak=; b=EchrURWjVs1TOps0DmcXOtLL2o7ocjmMztgtqrblW7hUVvRjGWF+rOKH9Tgsh78DZs Svy5Lx2WDoyuLphfsfxSydtXj+YWmYlP1elnWkc6UkEVCmWyNtnfqkF1/Jg99bHjx9DM bD0lHAtT/VsjOc4OBLjlZVsXhnZoEH9jqYax+u7KOY5zr65xkwK7uTv4/XlZAYVRt1A2 8y1cXnL9YcNnVpTUXXDlCWEJ/vjVTmVu+6rq0OjXE13WoApxp7GPhJaw23Ve7ZTfj2Ra 4zd26l8kJ/H8v5t3pTJwqxet1pI1hqU+VNgH7D7VKzhe514aJsQ5k8hZ8HYog4ro0Yuv Lqsw== MIME-Version: 1.0 X-Received: by 10.50.132.66 with SMTP id os2mr9989911igb.6.1426706887866; Wed, 18 Mar 2015 12:28:07 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.36.17.194 with HTTP; Wed, 18 Mar 2015 12:28:07 -0700 (PDT) In-Reply-To: <3923303.nkjJO958qy@ralph.baldwin.cx> References: <2085699.T9kJlc0rkf@ralph.baldwin.cx> <3923303.nkjJO958qy@ralph.baldwin.cx> Date: Wed, 18 Mar 2015 12:28:07 -0700 X-Google-Sender-Auth: IzYsK92v7LrsmGHB_X5zzigDRtw Message-ID: Subject: Re: What parts of UMA are part of the stable ABI? From: Adrian Chadd To: John Baldwin Content-Type: text/plain; charset=UTF-8 Cc: FreeBSD Current , Ryan Stone X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 18 Mar 2015 19:28:08 -0000 On 18 March 2015 at 08:23, John Baldwin wrote: > On Wednesday, March 18, 2015 11:19:21 AM Ryan Stone wrote: >> On Wed, Mar 18, 2015 at 10:24 AM, John Baldwin wrote: >> >> > I do think the normal zone callbacks passed to uma_zcreate() are too public >> > to change. Or at least, you would need to do some crazy ABI shim where you >> > have a uma_zcreate_new() that you map to uma_zcreate() via a #define for >> > the API, but include a legacy uma_zcreate() symbol that older modules can >> > call (and then somehow tag the old function pointers via an internal flag >> > in the zone and patch UMA to cast to the old function signatures for zones >> > with that flag). >> > >> >> I really wasn't clear here. I definitely don't think that changing the >> ctor, etc to accept a size_t is MFC'able, and I don't think that the >> problem (which is really only theoretical at this point) warrants an MFC to >> -stable. I was talking about potentially doing it in a separate commit to >> head, but that does leave -stable and head with a different API. This can >> be painful for downstream consumers to deal with, which is why I wanted >> comments. > > I actually think the API change to fix the zone callbacks is fine to change > in HEAD. I don't think that is too disruptive for folks who might be > sharing code across branches (they can use a local typedef to work around > it or some such). +1. This isn't exposed to userland, right? So I wouldn't worry about. Kernel progress can't be held back because we're afraid of kernel ABI changes that fix actual bugs. -adrian