From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 97CF843D11; Thu, 21 Mar 2024 09:30:56 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 75E8D42830; Thu, 21 Mar 2024 09:30:56 +0100 (CET) Received: from wfout5-smtp.messagingengine.com (wfout5-smtp.messagingengine.com [64.147.123.148]) by mails.dpdk.org (Postfix) with ESMTP id 29599402D7; Thu, 21 Mar 2024 09:30:54 +0100 (CET) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailfout.west.internal (Postfix) with ESMTP id 8233E1C000CF; Thu, 21 Mar 2024 04:30:51 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Thu, 21 Mar 2024 04:30:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=monjalon.net; h= cc:cc:content-transfer-encoding:content-type:content-type:date :date:from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to; s=fm2; t=1711009851; x=1711096251; bh=PkEIk39UM7hfsOhUw/TMIydIeo0m6jiil8ZdCJ8i5JA=; b= Pu0V3IDNzgm06o9smWiu6BVqEOYKksG5GqAFz9hF0cip1Fzb2W8v1OEl/cl6fHfK bYq+MOjKQVi7Ba0TcH8fCQ1pDk047tX4NElyrXn0xQQ5oLU5asV6xzmXbW3+4yL0 2vVm2r713z8Qj6aY37GDu6QKqY/33hKnUjQTl1it5fGrU024gC7f1AagkONg/qIs zMmwb0P/FL11DdIBaegaCTbv4KOnQbhakA5TuaVX7D5l2XVlPRKmRfGg+8t+I0fk i0Qobun9VKiuf0eLjntZyNo/dVNkc616nwNt+xEcgVDtPK/v0ceQuLRm4RSjOehe lQUs5znoKEcvlN/8b6xB5g== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:content-type:date:date:feedback-id:feedback-id :from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm2; t=1711009851; x= 1711096251; bh=PkEIk39UM7hfsOhUw/TMIydIeo0m6jiil8ZdCJ8i5JA=; b=Z aUZB+ek6/I8AZ7WgQ5TPukOv41yQwbh3QR1ewiiSPNg/UZyQDrgUb1ilL6nJmnTu BJAAHhptva7SwOIMcv2HYSgoipfI+hOBYCAZl1y5XMvUfUVXOUz8+hxQZjT2RSQN bRZ123xPDbn674BncdZM5PsevIhKvrRl8d5ZkrsyWgHfAYQkgu3wrhoO68I7sPeA ++zzLN2QEYlUof3Bdu7PcbEdtQMOR25XuWRJxG6mTK3MRoWPd5qzhEKgCsn1+Mbp 8CJzjUj0P9yZlatRt5rYgZ2h+UzXnOTnbal4cq0GZX/b3GLbotJQGEKPOtGT3aCC eaKErFmXiDpYEFNFhg60Q== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvledrleehgdduvddtucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvvefufffkjghfggfgtgesthfuredttddtjeenucfhrhhomhepvfhhohhm rghsucfoohhnjhgrlhhonhcuoehthhhomhgrshesmhhonhhjrghlohhnrdhnvghtqeenuc ggtffrrghtthgvrhhnpeeljeeitdefheetvddvvdetjedvleeuffdtheeludejfeekieeh jeeuhfehfeetleenucffohhmrghinheptghpphhrvghfvghrvghntggvrdgtohhmnecuve hluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepthhhohhmrghs sehmohhnjhgrlhhonhdrnhgvth X-ME-Proxy: Feedback-ID: i47234305:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 21 Mar 2024 04:30:49 -0400 (EDT) From: Thomas Monjalon To: "fengchengwen@huawei.com" , "Ma, WenwuX" Cc: "dev@dpdk.org" , "Jiale, SongX" , "stable@dpdk.org" Subject: Re: [PATCH v3] dmadev: fix structure alignment Date: Thu, 21 Mar 2024 09:30:48 +0100 Message-ID: <2631241.9Mp67QZiUf@thomas> In-Reply-To: References: <20240308053711.1260154-1-wenwux.ma@intel.com> <3047329.687JKscXgg@thomas> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org 21/03/2024 02:25, Ma, WenwuX: > Hi, Thomas > > From: Thomas Monjalon > > 20/03/2024 08:23, Wenwu Ma: > > > The structure rte_dma_dev needs to be aligned to the cache line, but > > > the return value of malloc may not be aligned to the cache line. When > > > we use memset to clear the rte_dma_dev object, it may cause a > > > segmentation fault in clang-x86-platform. > > > > > > This is because clang uses the "vmovaps" assembly instruction for > > > memset, which requires that the operands (rte_dma_dev objects) must > > > aligned on a 16-byte boundary or a general-protection exception (#GP) > > > is generated. > > > > > > Therefore, either additional memory is applied for re-alignment, or > > > the rte_dma_dev object does not require cache line alignment. The > > > patch chooses the former option to fix the issue. > > > > > > Fixes: b36970f2e13e ("dmadev: introduce DMA device library") > > > Cc: stable@dpdk.org > > > > > > Signed-off-by: Wenwu Ma > > [..] > > > - size = dma_devices_max * sizeof(struct rte_dma_dev); > > > - rte_dma_devices = malloc(size); > > > - if (rte_dma_devices == NULL) > > > + /* The dma device object is expected to align cacheline, but > > > + * the return value of malloc may not be aligned to the cache line. > > > + * Therefore, extra memory is applied for realignment. > > > + * note: We do not call posix_memalign/aligned_alloc because it is > > > + * version dependent on libc. > > > + */ > > > + size = dma_devices_max * sizeof(struct rte_dma_dev) + > > > + RTE_CACHE_LINE_SIZE; > > > + ptr = malloc(size); > > > + if (ptr == NULL) > > > return -ENOMEM; > > > - memset(rte_dma_devices, 0, size); > > > + memset(ptr, 0, size); > > > + > > > + rte_dma_devices = RTE_PTR_ALIGN(ptr, RTE_CACHE_LINE_SIZE); > > > > Why not using aligned_alloc()? > > https://en.cppreference.com/w/c/memory/aligned_alloc > > > > > because it is version dependent on libc. Which libc is required?