Fifth draft of the Y2038 design document

[Albert ARIBAUD]

Hi Joseph,

On Wed, 22 Feb 2017 21:16:29 +0000, Joseph Myers
<joseph@codesourcery.com> wrote :

> On Wed, 22 Feb 2017, Albert ARIBAUD wrote:
> 
> > Hi Joseph,
> > 
> > On Wed, 22 Feb 2017 20:55:39 +0000, Joseph Myers
> > <joseph@codesourcery.com> wrote :
> >   
> > > On Wed, 22 Feb 2017, Albert ARIBAUD wrote:
> > >   
>  [...]  
> > > 
> > > There are several such ABIs (ILP32 ABI for a 64-bit architecture) already 
> > > supported in glibc, e.g. MIPS n32, and all of them that don't already have 
> > > support for 64-bit time_t will need to have it added.  
> > 
> > I /was/ not planning on supporting such a scenario. :)
> > 
> > More seriously: is there already a list of these ABIs?  
> 
> I'm not convinced that is a meaningful question.  You can identify ABIs 
> with 32-bit time_t by e.g. building for different ABIs with 
> build-many-glibcs.py then compiling a test program with each compiler and 
> corresponding options.  Some such ABIs may require a 64-bit kernel.  Some 
> may work with both 32-bit and 64-bit kernels (e.g. 32-bit x86).  Some may 
> be for 32-bit-only architectures.
> 
> In all cases, whether the kernel is working with a 32-bit or 64-bit 
> address space is not relevant; you work with the syscall ABI as it is, 
> plus whatever additions are made to it in the course of the Y2038 work.
> 
> That said, I think the following ABIs use 64-bit register size in 
> userspace while being ILP32 ABIs.  You'll need to examine the code more 
> closely in each case to determine what size time_t is, and to what extent 
> if any 64-bit registers are involved in the syscall ABI.  There may be 
> other cases where 64-bit registers can in fact be used for what's normally 
> considered a 32-bit ABI (e.g. people have done some work on being able to 
> use 64-bit registers for 32-bit powerpc code, although the registers are 
> 32-bit for all purposes in the function-calling ABI).
> 
> AArch64 ILP32 (not yet in glibc)
> MIPS n32
> TileGX32
> x86_64 x32

Thanks. I'll look into these.

Cordialement,
Albert ARIBAUD
3ADEV