Return-path: Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:45468 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751737AbaLESbZ (ORCPT ); Fri, 5 Dec 2014 13:31:25 -0500 Date: Fri, 5 Dec 2014 18:31:13 +0000 From: Catalin Marinas To: Russell King - ARM Linux Cc: Arnd Bergmann , linux-wireless , "brcm80211-dev-list@broadcom.com" , "linux-kernel@vger.kernel.org" , Arend van Spriel , David Miller , "linux-arm-kernel@lists.infradead.org" Subject: Re: using DMA-API on ARM Message-ID: <20141205183113.GD31222@e104818-lin.cambridge.arm.com> (sfid-20141205_193143_362495_EBB8746B) References: <5481794E.4050406@broadcom.com> <4565667.WCBuNmaazQ@wuerfel> <20141205111114.GQ11285@n2100.arm.linux.org.uk> <20141205173839.GB31222@e104818-lin.cambridge.arm.com> <20141205182443.GX11285@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20141205182443.GX11285@n2100.arm.linux.org.uk> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, Dec 05, 2014 at 06:24:43PM +0000, Russell King - ARM Linux wrote: > On Fri, Dec 05, 2014 at 05:38:39PM +0000, Catalin Marinas wrote: > > On Fri, Dec 05, 2014 at 11:11:14AM +0000, Russell King - ARM Linux wrote: > > > In any case, wouldn't using a u64 type for "address" be better - isn't > > > "long long" 128-bit on 64-bit architectures? > > > > No, it's still 64-bit. There is no 128-bit integer in the C standard. > > Actually, that's a fallicy. > > The C99 standard (like previous versions) does not define exactly the > number of bits in each type. It defines ranks of type, and says that > lower ranks are a subrange of integers with higher ranks (for the same > signed-ness.) See section 6.2.5. > > So, it merely states that: > > range(char) <= range(short) <= range(int) <= range(long) <= range(long long) You are probably right, I haven't checked. But the ABI we use in Linux for 64-bit, LP64, defines long long as 64-bit. Gcc has a int128_t type but it's specific to this toolchain. -- Catalin