From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:43037) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ShSfq-0001Ku-3H for qemu-devel@nongnu.org; Wed, 20 Jun 2012 17:42:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ShSfo-0001nR-AZ for qemu-devel@nongnu.org; Wed, 20 Jun 2012 17:42:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:26641) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ShSfo-0001nA-2a for qemu-devel@nongnu.org; Wed, 20 Jun 2012 17:42:48 -0400 Date: Thu, 21 Jun 2012 00:42:27 +0300 From: "Michael S. Tsirkin" Message-ID: <20120620214227.GD25850@redhat.com> References: <1340087992-2399-1-git-send-email-benh@kernel.crashing.org> <1340087992-2399-4-git-send-email-benh@kernel.crashing.org> <4FE23DBF.9040706@codemonkey.ws> <20120620213217.GA25850@redhat.com> <4FE242D6.4060709@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FE242D6.4060709@codemonkey.ws> Subject: Re: [Qemu-devel] [PATCH 03/13] iommu: Add universal DMA helper functions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Richard Henderson , Eduard - Gabriel Munteanu , qemu-devel@nongnu.org, David Gibson On Wed, Jun 20, 2012 at 04:38:30PM -0500, Anthony Liguori wrote: > On 06/20/2012 04:32 PM, Michael S. Tsirkin wrote: > >On Wed, Jun 20, 2012 at 04:16:47PM -0500, Anthony Liguori wrote: > >>>diff --git a/hw/pci.h b/hw/pci.h > >>>index 7f223c0..ee669d9 100644 > >>>--- a/hw/pci.h > >>>+++ b/hw/pci.h > >>>@@ -558,10 +558,16 @@ static inline uint32_t pci_config_size(const PCIDevice *d) > >>> } > >>> > >>> /* DMA access functions */ > >>>+static inline DMAContext *pci_dma_context(PCIDevice *dev) > >>>+{ > >>>+ /* Stub for when we have no PCI iommu support */ > >>>+ return NULL; > >>>+} > >> > >>Why is all of this stuff static inline? > > > >Let's face it, most people don't need an MMU in their VM. > >inline stubs help make double sure we are not adding > >overhead for the sake of this niche case. > > It also makes for an overly complex pci.h with no obvious performance justification. > A stub in a header plus an offline empty function is even more useless code. inline stubs is standard procedure. > Let's not prematurely optimize here. > > Regards, > > Anthony Liguori It's not just an optimization. It is easier to see what's going on this way. -- MST