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Re: [PATCH v2 2/7] y2038: Introduce __ASSUME_64BIT_TIME define
- From: Stepan Golosunov <stepan at golosunov dot pp dot ru>
- To: Lukasz Majewski <lukma at denx dot de>
- Cc: Joseph Myers <joseph at codesourcery dot com>, libc-alpha at sourceware dot org, Arnd Bergmann <arnd at arndb dot de>, Paul Eggert <eggert at cs dot ucla dot edu>
- Date: Thu, 6 Jun 2019 10:50:27 +0400
- Subject: Re: [PATCH v2 2/7] y2038: Introduce __ASSUME_64BIT_TIME define
- References: <20190429104613.16209-1-lukma@denx.de> <20190429104613.16209-3-lukma@denx.de> <alpine.DEB.2.21.1904292138430.21580@digraph.polyomino.org.uk> <20190430110505.2a0c7d1a@jawa> <alpine.DEB.2.21.1905021431060.4027@digraph.polyomino.org.uk> <20190506165510.7a6c20d1@jawa> <alpine.DEB.2.21.1905071523000.3445@digraph.polyomino.org.uk> <20190508121840.39aaedcb@jawa> <20190531113753.h4ske4el2nxevxo6@sghpc.golosunov.pp.ru> <20190605183516.3a45d776@jawa>
05.06.2019 в 18:35:16 +0200 Lukasz Majewski написал:
> Hi Stepan,
>
> > 08.05.2019 в 12:18:40 +0200 Lukasz Majewski написал:
> > > Hi Joseph,
> > >
> > > > On Mon, 6 May 2019, Lukasz Majewski wrote:
> > > >
> > > > > > So, which is (or will be) the case in 5.1 release? Padding
> > > > > > ignored or not?
> > > > >
> > > > > As confirmed in the other mail - the padding is ignored in Linux
> > > > > kernel (and the fix patch for x32 is up its way to be
> > > > > pulled).
> > > >
> > > > Did the patch to ignore padding (for compat syscalls under 64-bit
> > > > kernels, non-x32) make it into the final 5.1 release?
> > >
> > > As fair as I can tell, it was not pulled to 5.1.
> >
> > The patch went into 5.1.5 and 5.2-rc1.
> >
> > So the question now is:
> >
> > Should Linux 5.1.0–5.1.4 be considered buggy and unsupported, or
> > should glibc clear padding around tv_nsec on 32-bit architectures when
> > __LINUX_KERNEL_VERSION < 0x050105 and 64-bit kernel exists?
>
> I would assume that the kernel is buggy for 5.1.0–5.1.4 on x32 (I
> don't know what would be the impact of such decision - to be more
> specific how many x32 ABI users would be affected).
x32 is irrelevant for this bug (as long as it has 64-bit tv_nsec in
glibc). All other 32-bit ABIs which can be used on 64-bit kernels are
affected.
> Moreover, I would add the condition __LINUX_KERNEL_VERSION >= 0x050105
> when we define __ASSUME_TIME64_SYSCALLS.
This won't help as _time64 syscalls should be called even when
__ASSUME_TIME64_SYSCALLS is not defined.