Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it

From: Joseph Myers
Date: Mon Nov 16 2015 - 07:36:27 EST

On Mon, 16 Nov 2015, Arnd Bergmann wrote:

> > It's not a matter of leaving anything out - these would simply use 64-bit
> > off_t (__off_t and __off64_t would be the same type) and the *64 versions
> > would be aliases, exactly the same as on 64-bit architectures. (And
> > _FILE_OFFSET_BITS handling would also be exactly the same as on 64-bit
> > architectures.) I see no reason for the set of off_t-related symbols that
> > exist, or which symbols are aliases of which others, to vary between pure
> > 64-bit systems and ILP32 ABIs (for 32-bit or 64-bit architectures) that
> > simply happen to have had 64-bit off_t from the start.
> Ok, fair enough. So we just change the global __OFF_T_TYPE definition
> in bits/typesizes.h and override it for all the existing 32-bit ports,
> correct?

Well, it's sysdeps/unix/sysv/linux/generic/bits/typesizes.h that's
relevant - so if future generic architectures will use 64-bit off_t, I
suppose the existing file could be cloned for existing generic
architectures with 32-bit support. And all the types involved in struct
stat are affected (e.g. ino_t), not just off_t. And getting the aliases
right may involve disentangling the different meanings of wordsize-64 into
different sysdeps directories. ("off_t is off64_t" and "stat is stat64"
are not the same thing. See MIPS n64.) And the design work needs to be
done on libc-alpha, not in a random discussion elsewhere.

Joseph S. Myers
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