linux-kernel - Re: [PATCH 01/27] [AARCH64] Fix utmp struct for compatibility reasons.

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Message-ID: <20160623043542.GA13449@yury-N73SV>
Date:	Thu, 23 Jun 2016 07:35:42 +0300
From:	Yury Norov <ynorov@...iumnetworks.com>
To:	Szabolcs Nagy <szabolcs.nagy@....com>
CC:	<libc-alpha@...rceware.org>, <linux-kernel@...r.kernel.org>,
	<nd@....com>, <arnd@...db.de>, <catalin.marinas@....com>,
	<marcus.shawcroft@....com>, <philb@....org>, <davem@...emloft.net>,
	<maxim.kuvyrkov@...aro.org>, <joseph@...esourcery.com>,
	<pinskia@...il.com>, Andrew Pinski <apinski@...ium.com>
Subject: Re: [PATCH 01/27] [AARCH64] Fix utmp struct for compatibility
 reasons.

On Tue, Jun 21, 2016 at 11:14:54AM +0100, Szabolcs Nagy wrote:
> On 21/06/16 06:06, Yury Norov wrote:
> > From: Andrew Pinski <apinski@...ium.com>
> > 
> > NOTE This is an ABI change for AARCH64.
> > If you have some AARCH32 and AARCH64 applications and they both use
> > utmp, one of them will fail due to the use of time_t inside the
> > utmp binary format.
> > 
> > This fixes the problem by setting __WORDSIZE_TIME64_COMPAT32.
> 
> i think changing the abi now is not ok.
> 
> this is BZ 17470 and i think it should be discussed separately
> from ilp32.
> 
> if it's possible to detect the utmp file format, that would
> allow a reasonable fix, the way glibc changes the struct def
> based on lp64 targets is non-conforming.

Hi Joseph, Szabolcs,

I revised it and found that we don't need __WORDSIZE_TIME64_COMPAT32
because ilp32 already has 32-bit time_t.
So for now sysdeps/aarch64/bits/wordsize.h is looking like this:
        #ifdef __LP64__
        # define __WORDSIZE                    64
        #else
        # define __WORDSIZE                    32
        # define __WORDSIZE32_SIZE_ULONG       1
        # define __WORDSIZE32_PTRDIFF_LONG     1
        #endif

is it OK? Andrew?