Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758875AbaDXShb (ORCPT ); Thu, 24 Apr 2014 14:37:31 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:52065 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758725AbaDXSh1 (ORCPT ); Thu, 24 Apr 2014 14:37:27 -0400 Message-ID: <535959DF.6050009@codesourcery.com> Date: Fri, 25 Apr 2014 02:37:19 +0800 From: Chung-Lin Tang User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Catalin Marinas CC: "Pinski, Andrew" , Ley Foon Tan , Arnd Bergmann , "H. Peter Anvin" , Linux-Arch , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , Andrew Pinski , "Tang, Chung-Lin" Subject: Re: [PATCH 00/28] nios2 Linux kernel port References: <1397824031-4892-1-git-send-email-lftan@altera.com> <5354AD36.5090809@zytor.com> <16597012.pEkDc99HDN@wuerfel> <5357FF8E.9010809@codesourcery.com> <5358AE96.9010006@codesourcery.com> <5358D17D.1040609@codesourcery.com> <20140424152819.GI8521@arm.com> In-Reply-To: <20140424152819.GI8521@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 24 Apr 2014 18:37:24.0477 (UTC) FILETIME=[3C3FD2D0:01CF5FEC] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/4/24 11:28 PM, Catalin Marinas wrote: > On Thu, Apr 24, 2014 at 09:55:25AM +0100, Chung-Lin Tang wrote: >> On 2014/4/24 02:26 PM, Chung-Lin Tang wrote: >>> On 2014/4/24 上午 02:15, Pinski, Andrew wrote: >>>> >>>>>> On Apr 23, 2014, at 10:59 AM, "Chung-Lin Tang" wrote: >>>>>> >>>>>>>> On 2014/4/22 07:20 PM, Ley Foon Tan wrote: >>>>>>>> On Tue, Apr 22, 2014 at 6:56 PM, Arnd Bergmann wrote: >>>>>>>>>>>> On Tuesday 22 April 2014 18:37:11 Ley Foon Tan wrote: >>>>>>>>>>>>>>>> Hi Arnd and Peter Anvin, >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Other than 64-bit time_t, clock_t and suseconds_t, can you confirm >>>>>>>>>>>>>>>> that we don't need to have 64 bit off_t? See detail in link below. >>>>>>>>>>>>>>>> I can submit the patches for 64-bit time changes >>>>>>>>>>>>>>>> (include/asm-generic/posix_types.h and other archs) if everyone is >>>>>>>>>>>>>>>> agreed on this. >>>>>>>>>>>> >>>>>>>>>>>> Yes. >>>>>>>> Okay, will doing that. >>>>>> >>>>>> I believe that arm64 ILP32 will also be affected. What is the status of >>>>>> this configuration? Has the glibc/kernel ABI been finalized? >>>> Not yet. I am still working out the signal handling part. But we >>>> already agreed on 64bit time_t, clock_t, and suseconds_t. And we >>>> agreed to a 64bit offset_t too. >>>> >>>> On a related note suseconds in the timespec in posix is defined to >>>> be long. So it would nice if the kernel ignores the upper 32bits so >>>> we (glibc developers) can fix this for new targets including x32 >>>> and arm64/ilp32. >>> >>> Hmm, but that means for purely 32-bit architectures like nios2, which >>> unlike x86_64 or arm64, never has a 64-bit mode, suseconds_t as a 64-bit >>> type in the kernel is simply wasted. >> >> The more I think of this, the more I feel that suseconds_t should jsut >> be 'long', not strictly 64-bitified. An ILP32 sub-mode in a 64-bit >> kernel should be using compat_* code paths, something like a >> COMPAT_USE_32BIT_SUSECONDS case. > > ILP32 mode should use LP64 syscalls as much as possible and that's the > aim with arm64 as well (of course, we still have a few that wouldn't be > possible and we route them via compat). > > But here if time_t is 64-bit while susecconds_t is 32-bit, the compat > code wouldn't help. Why not? You can define the arm64 'struct compat_timeval' with suseconds_t as s32, and add the 32<-->64 case in the compat_get/put_timeval path, triggered when the process is ILP32 (test wrapped in the above hypothetical COMPAT_USE_32BIT_SUSECONDS macro). Similar to how x32 does COMPAT_USE_64BIT_TIME. Chung-Lin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/