From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55A72C433E0 for ; Tue, 28 Jul 2020 16:26:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22F552070B for ; Tue, 28 Jul 2020 16:26:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595953577; bh=8e/IpfH0tEGQw4eRgZPxqGN1xvDTdZgV9fdlNOZ6og8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=LJXkqM0NDY/Nn+9d9oAmRSp31rn+NrI7+ix2rd3LGyjaBG64kj8fuy0+ttzAFmtJh 3/GIrmyQ1oAHJhsNCjblxNe3ELtFAVYUo/GzWQIF1WQkasSit+S6Y3r0R8DCR/WLjd YyQ1h9i0VixAuzfTKQ+TZbzZyVlctSHcPGRHYCp8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731349AbgG1Q0Q (ORCPT ); Tue, 28 Jul 2020 12:26:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:43994 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731192AbgG1Q0Q (ORCPT ); Tue, 28 Jul 2020 12:26:16 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5655E20663; Tue, 28 Jul 2020 16:26:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595953575; bh=8e/IpfH0tEGQw4eRgZPxqGN1xvDTdZgV9fdlNOZ6og8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=V+tGZn7u7iHhNApaehm+Ii1gc1McMh/MHLoyFFsy9dWvgCCd15BxjY9uNB9TiDeSP Ly4qXDCEvsM8EW1V7Xaz1wq0jzbcYeFm84ur6UnndE3m6kBc4gamvIYj7tNKAjbdtS IwDw05oGkUlZB2La5VmWtEZkkSs8rhv8JNoUEQZM= Date: Tue, 28 Jul 2020 18:26:08 +0200 From: Greg KH To: Jonathan Lemon Cc: netdev@vger.kernel.org, kernel-team@fb.com Subject: Re: [RFC PATCH v2 10/21] netgpu: add network/gpu/host dma module Message-ID: <20200728162608.GA4181352@kroah.com> References: <20200727224444.2987641-1-jonathan.lemon@gmail.com> <20200727224444.2987641-11-jonathan.lemon@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200727224444.2987641-11-jonathan.lemon@gmail.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jul 27, 2020 at 03:44:33PM -0700, Jonathan Lemon wrote: > From: Jonathan Lemon > > Netgpu provides a data path for zero-copy sends and receives > without having the host CPU touch the data. Protocol processing > is done on the host CPU, while data is DMA'd to and from DMA > mapped memory areas. The initial code provides transfers between > (mlx5 / host memory) and (mlx5 / nvidia GPU memory). > > The use case for this module are GPUs used for machine learning, > which are located near the NICs, and have a high bandwidth PCI > connection between the GPU/NIC. Do we have such a GPU driver in the kernel today? We can't add new apis/interfaces for no in-kernel users, as you well know. There's lots of crazyness in this patch, but this is just really odd: > +#if IS_MODULE(CONFIG_NETGPU) > +#define MAYBE_EXPORT_SYMBOL(s) > +#else > +#define MAYBE_EXPORT_SYMBOL(s) EXPORT_SYMBOL(s) > +#endif Why is that needed at all? Why does no one else in the kernel need such a thing? And why EXPORT_SYMBOL() and not EXPORT_SYMBOL_GPL() (I have to ask). thanks, greg k-h