From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH 00/28] nios2 Linux kernel port Date: Thu, 24 Apr 2014 16:28:19 +0100 Message-ID: <20140424152819.GI8521@arm.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from fw-tnat.austin.arm.com ([217.140.110.23]:17931 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757202AbaDXP3C (ORCPT ); Thu, 24 Apr 2014 11:29:02 -0400 Content-Disposition: inline In-Reply-To: <5358D17D.1040609@codesourcery.com> Content-Language: en-US Sender: linux-arch-owner@vger.kernel.org List-ID: To: Chung-Lin Tang 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" 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 =E4=B8=8A=E5=8D=88 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 st= atus 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.=20 > >> > >> 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 s= o > >> we (glibc developers) can fix this for new targets including x32 > >> and arm64/ilp32.=20 > >=20 > > Hmm, but that means for purely 32-bit architectures like nios2, whi= ch > > unlike x86_64 or arm64, never has a 64-bit mode, suseconds_t as a 6= 4-bit > > type in the kernel is simply wasted. >=20 > The more I think of this, the more I feel that suseconds_t should jsu= t > 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. --=20 Catalin