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[2620:137:e000::3:2]) by mx.google.com with ESMTPS id t13-20020a17090aae0d00b002791035445esi8901831pjq.76.2023.10.09.01.39.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Oct 2023 01:39:56 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) client-ip=2620:137:e000::3:2; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=liAKXVmo; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by agentk.vger.email (Postfix) with ESMTP id 0EF4D804C1B7; Mon, 9 Oct 2023 01:39:54 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at agentk.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234477AbjJIIjs (ORCPT + 99 others); Mon, 9 Oct 2023 04:39:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234407AbjJIIjr (ORCPT ); Mon, 9 Oct 2023 04:39:47 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C5DF9F; Mon, 9 Oct 2023 01:39:46 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BABC1C433C7; Mon, 9 Oct 2023 08:39:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696840785; bh=FtkEjzcRbtlsYh6eaM0c3E6zfK54DBTflsaso2PDaac=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=liAKXVmo9AnwBPBY7iA753zrNtz/sl+uX7W/61C1NyJqXC89aVs9REWiHYda8qEgN xmyynk4NPZOifXJZETETOHztGukFxU3lXtEN1p8H9tPn+AA0QorG2Ixo+lXoV3F0dr 8BVHO6zk8ozWcfUhoZM6EebttFBs13w0tJ+ch7RfvstMS4M0Qeh4GNcRfxeuCzv0dR FxsTz2QwvTQvWDYlour0m/wRH00+iS2PkwtknrWfAqmtaDPLINTu2h5b+0fML9XqhH Ho8ibhn/skq6m+aOJlRTvexwXS2TJs/fo3DZ+pnOzeCYUloWiRejztd4VPqHYJ9zfj BIkx9ZIqs4fFw== Date: Mon, 9 Oct 2023 11:38:51 +0300 From: Mike Rapoport To: Axel Rasmussen Cc: Alejandro Colomar , Peter Xu , linux-man@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 01/10] userfaultfd.2: briefly mention two-step feature handshake process Message-ID: <20231009083851.GF3303@kernel.org> References: <20230919190206.388896-1-axelrasmussen@google.com> <20230919190206.388896-2-axelrasmussen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230919190206.388896-2-axelrasmussen@google.com> X-Spam-Status: No, score=2.4 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, RCVD_IN_SBL_CSS,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on agentk.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (agentk.vger.email [0.0.0.0]); Mon, 09 Oct 2023 01:39:54 -0700 (PDT) X-Spam-Level: ** On Tue, Sep 19, 2023 at 12:01:57PM -0700, Axel Rasmussen wrote: > This process is critical for programs which depend on extra features, so > it's worth mentioning here. > > Future commits will much more fully describe it in ioctl_userfaultfd.2. > > Signed-off-by: Axel Rasmussen Reviewed-by: Mike Rapoport (IBM) > --- > man2/userfaultfd.2 | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 > index 40354065c..1b2af22f9 100644 > --- a/man2/userfaultfd.2 > +++ b/man2/userfaultfd.2 > @@ -200,8 +200,9 @@ the application must enable it using the > .B UFFDIO_API > .BR ioctl (2) > operation. > -This operation allows a handshake between the kernel and user space > -to determine the API version and supported features. > +This operation allows a two-step handshake between the kernel and user space > +to determine what API version and features the kernel supports, > +and then to enable those features user space wants. > This operation must be performed before any of the other > .BR ioctl (2) > operations described below (or those operations fail with the > -- > 2.42.0.459.ge4e396fd5e-goog > > -- Sincerely yours, Mike.