From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:49816) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ShSjo-0002Ys-Eo for qemu-devel@nongnu.org; Wed, 20 Jun 2012 17:46:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ShSjm-0002tb-PB for qemu-devel@nongnu.org; Wed, 20 Jun 2012 17:46:56 -0400 Received: from mail-pb0-f45.google.com ([209.85.160.45]:48578) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ShSjm-0002tS-Ih for qemu-devel@nongnu.org; Wed, 20 Jun 2012 17:46:54 -0400 Received: by pbbro12 with SMTP id ro12so1215629pbb.4 for ; Wed, 20 Jun 2012 14:46:52 -0700 (PDT) Message-ID: <4FE244C9.1090203@codemonkey.ws> Date: Wed, 20 Jun 2012 16:46:49 -0500 From: Anthony Liguori MIME-Version: 1.0 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> <20120620214227.GD25850@redhat.com> In-Reply-To: <20120620214227.GD25850@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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: "Michael S. Tsirkin" Cc: Richard Henderson , Eduard - Gabriel Munteanu , qemu-devel@nongnu.org, David Gibson On 06/20/2012 04:42 PM, Michael S. Tsirkin wrote: > 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. Look at 8/13. They don't stay stubs for long. Regards, Anthony Liguori > >> 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. >