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

From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it
Date	2015-11-15 16:20 +0100
Message-ID	<qv7fY-34y-9@gated-at.bofh.it> (permalink)
References	<qqwRH-3eC-3@gated-at.bofh.it> <quoCe-8cf-35@gated-at.bofh.it> <qupeV-eJ-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Friday 13 November 2015 17:10:44 Arnd Bergmann wrote:
> On Friday 13 November 2015 07:38:49 Andrew Pinski wrote:
> > On Fri, Nov 13, 2015 at 7:34 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > > On Thursday 12 November 2015 14:47:18 Andreas Schwab wrote:
> > >> Arnd Bergmann <arnd@arndb.de> writes:
> > >>
> > >> > On Thursday 12 November 2015 10:44:55 Andreas Schwab wrote:
> > >> >> Arnd Bergmann <arnd@arndb.de> writes:
> > >> >>
> > >> >> > What do you mean with 32-bit off_t?
> > >> >>
> > >> >> An ABI with 32-bit off_t, ie. all currently implemented 32-bit ABIs.
> > >> >>
> > >> >> > Do you mean that glibc emulates a 32-bit off_t on top of the 64-bit
> > >> >> > __kernel_loff_t?
> > >> >>
> > >> >> Glibc is bridging the user-space ABI to the kernel ABI.
> > >> >
> > >> > Ok, but why?
> > >>
> > >> That's how the ABI is defined right now.  I didn't make that up.
> > >
> > > Ok, I guess it will remain a mystery then.
> > 
> > The biggest question is here is how much compatibility do we want with
> > other 32bit ABIs?
> > Do we want off_t to be 32bit or 64bit?
> 
> I would much prefer off_t to be defined as __kernel_loff_t unconditionally,
> with no support for _FILE_OFFSET_BITS == 32. This is at least what I had
> in mind when I wrote the asm-generic/unistd.h header.
> 
> We should probably find out what happened for the other glibc ports that
> were implemented for the architectures using this. It's possible that
> there was a good reason for supporting _FILE_OFFSET_BITS == 32 at the
> time, but I can't think of one and maybe it is one that is no longer
> valid.
> 
> Do you know what x86/x32 does for off_t? Do they also implement both
> _FILE_OFFSET_BITS == 32 and _FILE_OFFSET_BITS == 64 on top of the
> 64-bit __kernel_off_t?

I just did a little bit of digging through glibc history and found that
Chris Metcalf added the files that are now in
sysdeps/unix/sysv/linux/generic/wordsize-32/ and that provide the
implementation for 32-bit off_t in glibc on top of the 64-bit
__kernel_off_t.

Chris, do you remember what led to that? Do you think we still need
to have 32-bit off_t on all new architectures, or could we move
on to making 64-bit off_t the default when adding a port?

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Thread

[RFC PATCH v6 00/17] ILP32 for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  [PATCH v6 03/17] arm64: rename COMPAT to AARCH32_EL0 in Kconfig Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  [PATCH v6 04/17] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  [PATCH v6 10/17] arm64:ilp32: support core dump generation for ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  [PATCH v6 08/17] arm64:ilp32: share HWCAP between LP64 and ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  [PATCH v6 14/17] aarch64: ilp32: use generic stat64 structure Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
    Re: [PATCH v6 14/17] aarch64: ilp32: use generic stat64 structure Arnd Bergmann <arnd@arndb.de> - 2015-11-05 15:20 +0100
  [PATCH v6 01/17] arm64:ilp32: add documentation on the ILP32 ABI for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
    Re: [PATCH v6 01/17] arm64:ilp32: add documentation on the ILP32 ABI for ARM64 Arnd Bergmann <arnd@arndb.de> - 2015-11-05 15:40 +0100
  [PATCH v6 11/17] ptrace: Allow compat to use the native siginfo Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
    Re: [PATCH v6 11/17] ptrace: Allow compat to use the native siginfo Arnd Bergmann <arnd@arndb.de> - 2015-11-05 15:00 +0100
  [PATCH v6 15/17] arm64:ilp32: use the native siginfo instead of the compat siginfo Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  [PATCH v6 07/17] arm64:ilp32: add is_ilp32_compat_{task,thread} and TIF_32BIT_AARCH64 Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
    Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-05 15:00 +0100
    Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Andreas Schwab <schwab@suse.de> - 2015-11-11 19:00 +0100
      Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-11 21:50 +0100
        Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Andreas Schwab <schwab@suse.de> - 2015-11-12 00:10 +0100
          Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-12 00:30 +0100
            Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Andreas Schwab <schwab@suse.de> - 2015-11-12 10:00 +0100
              Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-12 10:30 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Andreas Schwab <schwab@suse.de> - 2015-11-12 10:50 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-12 14:30 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Andreas Schwab <schwab@suse.de> - 2015-11-12 14:50 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-13 16:40 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Andrew Pinski <pinskia@gmail.com> - 2015-11-13 16:40 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-13 17:20 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-15 16:20 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Joseph Myers <joseph@codesourcery.com> - 2015-11-16 11:20 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-16 12:10 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Joseph Myers <joseph@codesourcery.com> - 2015-11-16 12:20 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-16 12:50 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Joseph Myers <joseph@codesourcery.com> - 2015-11-16 13:10 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-16 13:20 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Joseph Myers <joseph@codesourcery.com> - 2015-11-16 13:40 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-16 14:20 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Andreas Schwab <schwab@suse.de> - 2015-11-16 14:40 +0100
                Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-11-16 15:00 +0100
  [PATCH v6 17/17] arm64:ilp32: add ARM64_ILP32 to Kconfig Yury Norov <ynorov@caviumnetworks.com> - 2015-11-03 00:40 +0100
  Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Andreas Schwab <schwab@suse.de> - 2015-11-05 12:40 +0100
    Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Andrew Pinski <pinskia@gmail.com> - 2015-11-05 14:50 +0100
      Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Andreas Schwab <schwab@suse.de> - 2015-11-09 11:10 +0100
        Re: [RFC PATCH v6 00/17] ILP32 for ARM64 "Zhangjian (Bamvor)" <bamvor.zhangjian@huawei.com> - 2015-11-11 08:30 +0100
          Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Andreas Schwab <schwab@suse.de> - 2015-11-11 09:50 +0100
      Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Andreas Schwab <schwab@suse.de> - 2015-11-09 14:30 +0100
        Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Arnd Bergmann <arnd@arndb.de> - 2015-11-09 15:30 +0100
          Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Andreas Schwab <schwab@suse.de> - 2015-11-09 15:40 +0100
            Re: [RFC PATCH v6 00/17] ILP32 for ARM64 Arnd Bergmann <arnd@arndb.de> - 2015-11-09 15:40 +0100
              Re: [RFC PATCH v6 00/17] ILP32 for ARM64 pinskia@gmail.com - 2015-11-09 16:10 +0100

csiph-web