From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E9F57535DE for ; Mon, 15 Apr 2024 10:10:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713175843; cv=none; b=kqoNo4n/XhSOWjUb2+vTxdHhELRijkNSUikoSXaBi60QZF10ADWuKWokKBcSIHuISt1V4YObK61Mb40Q8JI9KuDyCMSULyX2EgTte916mTRBAL9X9vUOhDTu3UZBOpdwxqrjrWeyUzwVaunngoEcLdogWY5IUpoJnLdsl+oUnNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713175843; c=relaxed/simple; bh=xtEvJXeB7TFIKE1VSuFziriDSPPc8slBHNGUqnsibA8=; h=Date:From:To:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LuM523fERl12v/0prN+tjG/UxFoSE3HOSOiUpvA1IVl/ZJjLyCxFeRvHDpG7BSgLtPLBP2VGcOwRL5AMuJXGhRmSrTAmx6sbw4h3JtYcrAG4Goyy39xxEWuaBj7NLvreCevbM2wgdjYBgCtxGc4n/LBB/CZk9TApkZuRHQq+29k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=bXufvXnX; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="bXufvXnX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Date:From:Subject:Message-ID:MIME-Version: Content-Type; bh=b3HAD4ydMoQfpSaOVQmz9wRl5t2xMfb3rTewFQHV5lQ=; b=bXufvXnXxll1Dasid2WxB8u9Pm3SIOmQuFCgxvYsrtYF59C+Onx5RdgFwvenTj 6oWhCd+cdQ0hZSOlLOo1AJcQGv0Ux1xd5WlgXxwJL2vRgXBjDtQ7tE8IwwuyGdLh TFDQa20KPpYkFrGtnqYH6C1Qy5EP/rHTFXEb1vJSn3JWk= Received: from localhost (unknown [183.81.182.182]) by gzga-smtp-mta-g1-2 (Coremail) with SMTP id _____wDnL50S_RxmJRxpAQ--.8924S2; Mon, 15 Apr 2024 18:10:27 +0800 (CST) Date: Mon, 15 Apr 2024 18:10:26 +0800 From: Honggang LI To: linux-rdma@vger.kernel.org Subject: Re: Question about extra 40 bytes needed for UD receive buffer Message-ID: References: Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CM-TRANSID:_____wDnL50S_RxmJRxpAQ--.8924S2 X-Coremail-Antispam: 1Uf129KBjvdXoW7Xr4xJF18Kw17WFWDKw45ZFb_yoW3GrXEkF Z7ur1DJ3W7Xr4Utw1Iyw45JrW2ya9xCrWF9r1xWrnYkryfKr45ZFn8WF9Ykw15CF4S9Fy5 WryfGw18ZwnxXjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7sRtyxR7UUUUU== X-CM-SenderInfo: 5krqwwxdqjzxi6rwjhhfrp/1tbiWxXBRWV4IPM4DQAAsx On Mon, Apr 15, 2024 at 10:55:12AM +0800, Honggang LI wrote: > Subject: Question about extra 40 bytes needed for UD receive buffer > From: Honggang LI > Date: Mon, 15 Apr 2024 10:55:12 +0800 > > However, I'm confused by the dump of `mckey` receive buffer. The flag > `IBV_WC_GRH` is set in `ibv_wc.wc_flags`, but there is no GRH in > the receive buffer. Received data starts from the *first* byte of > receive buffer. As multicast over UD QP only, can someone please explian > why there is no GRH in receive buffer and the data starts from the first > bytes of receive buffer with `IBV_WC_GRH` was set? Please ignore this. I made a mistake with the offset of the grh. There is a valid IP header in the receive buffer of 'mckey'.