From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/6982 Path: news.gmane.org!not-for-mail From: "H.J. Lu" Newsgroups: gmane.linux.kernel,gmane.linux.ports.arm.kernel,gmane.linux.lib.musl.general,gmane.comp.lib.glibc.alpha Subject: Re: [PATCHv3 00/24] ILP32 support in ARM64 Date: Wed, 11 Feb 2015 10:33:32 -0800 Message-ID: References: <20141002155217.GH32147@e104818-lin.cambridge.arm.com> <20150210181302.GA23886@brightrain.aerifal.cx> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1423679628 20660 80.91.229.3 (11 Feb 2015 18:33:48 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 11 Feb 2015 18:33:48 +0000 (UTC) Cc: Catalin Marinas , Andrew Pinski , linux-arm-kernel@lists.infradead.org, LKML , Andrew Pinski , musl@lists.openwall.com, GNU C Library To: Rich Felker Original-X-From: linux-kernel-owner@vger.kernel.org Wed Feb 11 19:33:40 2015 Return-path: Envelope-to: glk-linux-kernel-3@plane.gmane.org Original-Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YLc6V-00051f-4J for glk-linux-kernel-3@plane.gmane.org; Wed, 11 Feb 2015 19:33:39 +0100 Original-Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754037AbbBKSde (ORCPT ); Wed, 11 Feb 2015 13:33:34 -0500 Original-Received: from mail-oi0-f45.google.com ([209.85.218.45]:64990 "EHLO mail-oi0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753094AbbBKSdd (ORCPT ); Wed, 11 Feb 2015 13:33:33 -0500 Original-Received: by mail-oi0-f45.google.com with SMTP id i138so17095472oig.4 for ; Wed, 11 Feb 2015 10:33:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=1+o96W3r8ZxNBkZu+eeZM3+1iQRVj6SuiaJDLnGhN9c=; b=Enpnybn4nqmr5X7BYLgGuS4Q+2v9HNq/TiLdmH+Cmtoird/Vgix9bwo/bVihi4Nisw 0rTbCKtzSM/ZwvpWbD6e/bACtXNdgyTbkHMXKp0gYJH+h/DEH6U8WKd6j3vWI01gAOPq JqOHPkrfzQPfx0usDKiJ8h0VEIZWDPAUjCrXwptLtsySrhB6dHZxa5lFphKgcJ4DQ+CB GCR559JnoYjmMUrb678WdflIBabS8FKto3OrfpG3xr//Z/FTqBbo5a9pKvThDIRt921r MbB8Ye4Eaq/zsaFGtd7DF/126K1tEWd5ZTEdCpuRtjpgmEV68rJzGlLevLIvL/DyJspS ME3g== X-Received: by 10.202.196.137 with SMTP id u131mr18996505oif.78.1423679612746; Wed, 11 Feb 2015 10:33:32 -0800 (PST) Original-Received: by 10.76.134.102 with HTTP; Wed, 11 Feb 2015 10:33:32 -0800 (PST) In-Reply-To: <20150210181302.GA23886@brightrain.aerifal.cx> Original-Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Xref: news.gmane.org gmane.linux.kernel:1886680 gmane.linux.ports.arm.kernel:392793 gmane.linux.lib.musl.general:6982 gmane.comp.lib.glibc.alpha:49145 Archived-At: On Tue, Feb 10, 2015 at 10:13 AM, Rich Felker wrote: > On Thu, 2 Oct 2014 at 16:52:18 +0100, Catalin Marinas wrote: >> On Wed, Sep 03, 2014 at 10:18:54PM +0100, Andrew Pinski wrote: >> > New version with all of the requested changes. Updated to the >> > latest sources. >> > >> > Notable changes from the previous versions: >> > VDSO code has been factored out to be easier to understand and >> > easier to maintain. >> > Move the config option to the last thing that gets added. >> > Added some extra COMPAT_* macros for core dumping for easier usage. >> >> Apart from a few comments I've made, I would also like to see non-empty >> commit logs and long line wrapping (both in commit logs and >> Documentation/). Otherwise, the patches look fine. >> >> So what are the next steps? Are the glibc folk ok with the ILP32 Linux >> ABI? On the kernel side, what I would like to see: > > I don't know if this has been discussed on libc-alpha yet or not, but > I think we need to open a discussion of how it relates to open glibc > bug #16437, which presently applies only to x32 (ILP32 ABI on x86_64): > > https://sourceware.org/bugzilla/show_bug.cgi?id=16437 Please leave x32 out of this discussion. I have resolved this bug as WONTFIX. > While most of the other type changes proposed (I'm looking at > https://lkml.org/lkml/2014/9/3/719) are permissible and simply > ugly/undesirable, defining struct timespec with tv_nsec having any > type other than long conflicts with the requirements of C11 and POSIX, > and WG14 is unlikely to be interested in changing the C language > because the Linux kernel has the wrong type in timespec. > > Note that on aarch64 ILP32, the consequences of not fixing this right > away will be much worse than on x32, since aarch64 (at least as I > understand it) supports big endian where it's not just a matter of > sign-extending the value from userspace and ignoring the padding, but > rather changing the offset of the tv_nsec member. > > Working around the discrepencies in userspace IS possible, but ugly. > We do it in musl libc for x32 right now -- see: > > http://git.musl-libc.org/cgit/musl/tree/arch/x32/syscall_arch.h?id=v1.1.6 > http://git.musl-libc.org/cgit/musl/tree/arch/x32/src/syscall_cp_fixup.c?id=v1.1.6 You are free to do what you feel appropriate. I have no plans to change x32 on this in glibc at this moment. > I imagine the workarounds in glibc might need to be considerably more > widespread and uglier. > > Whatever happens on the kernel side, this needs to be coordinated with > userspace (glibc, etc.) properly so that the type error (glibc bug > 16437) is not propagated into a new target that we actually want > people to use. I'd really like it if other undesirable type changes > could be cleaned up too, but perhaps that's too much to ask from the > kernel side. > > Rich -- H.J.