From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH v2 00/21] Allow compile-testing NO_DMA (drivers) Date: Tue, 17 Apr 2018 19:48:01 +0200 Message-ID: References: <1521208314-4783-1-git-send-email-geert@linux-m68k.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Ulf Hansson , Wolfram Sang , linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fpga-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "open list:REMOTE PROCESSOR \(REMOTEPROC\) SUBSYSTEM" , Linux-ALSA , Bjorn Andersson , Eric Anholt , netdev , MTD Maling List , Linux I2C , linux1394-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Christoph Hellwig , Stefan Wahren , Boris Brezillon , "James E . J . Bottomley" , Herbert Xu , scsi , Richard Weinberger , Jassi Brar , Marek Vasut , "open list:SERI To: Rob Herring Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: netdev.vger.kernel.org Hi Rob, On Thu, Apr 5, 2018 at 2:32 AM, Rob Herring wrote: > On Fri, Mar 16, 2018 at 8:51 AM, Geert Uytterhoeven > wrote: >> If NO_DMA=y, get_dma_ops() returns a reference to the non-existing >> symbol bad_dma_ops, thus causing a link failure if it is ever used. >> >> The intention of this is twofold: >> 1. To catch users of the DMA API on systems that do no support the DMA >> mapping API, >> 2. To avoid building drivers that cannot work on such systems anyway. >> >> However, the disadvantage is that we have to keep on adding dependencies >> on HAS_DMA all over the place. >> >> Thanks to the COMPILE_TEST symbol, lots of drivers now depend on one or >> more platform dependencies (that imply HAS_DMA) || COMPILE_TEST, thus >> already covering intention #2. Having to add an explicit dependency on >> HAS_DMA here is cumbersome, and hinders compile-testing. > > The same can be said for CONFIG_IOMEM and CONFIG_OF. Any plans to > remove those too? CONFIG_IOMEM is mostly just a !CONFIG_UM option. Perhaps, if time permits... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds