Re: [RFC5 PATCH v6 00/21] ILP32 for ARM64

[Arnd Bergmann]

On Saturday 26 March 2016 20:36:43 Zhangjian wrote:
> Hi, Arnd
> 
> On 2016/3/21 17:43, Arnd Bergmann wrote:
> > On Monday 21 March 2016 10:07:49 Andreas Schwab wrote:
> >> This patch may fix a few LTP tests.
> >>
> >
> > Thanks for analyzing.
> >
> >> diff --git a/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h b/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h
> >> index 3631903..d1010db 100644
> >> --- a/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h
> >> +++ b/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h
> >> @@ -25,18 +25,29 @@
> >>   #define __O_NOFOLLOW	0100000
> >>   #define __O_DIRECT	0200000
> >>
> >> -#define __O_LARGEFILE	0
> >> +#ifdef __ILP32__
> >> +# define __O_LARGEFILE	0400000
> >> +#else
> >> +# define __O_LARGEFILE	0
> >> +#endif
> >>
> >
> > I guess this means I screwed up when I said I'd merged the kernel patch
> > that Yury did to fix it, sorry about that.
> >
> > We need the patch to make all new architecture in the kernel default to
> > O_LARGEFILE, and not do this in user space. I'd suggest now to keep the
> > patches as part of the ILP32 series after all, to make sure they are
> > merged at the point when they are needed.
> 
> I am a little bit confuse about off_t. In "[PATCH 08/33] 32-bit
> ABI: introduce ARCH_32BIT_OFF_T config option", it mentioned that all
> the new 32bit architecture should use 64bit off_t.

Ah, so it is part of the series. I had not checked that here.

> Should we define off_t in aarch64(for both ilp32 and lp64) in
> typesize.h as following?
> 
> diff --git a/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h b/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h
> index 7073493..13b77c5 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h
> +++ b/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h
> @@ -33,7 +33,7 @@
>   #define __INO64_T_TYPE         __UQUAD_TYPE
>   #define __MODE_T_TYPE          __U32_TYPE
>   #define __NLINK_T_TYPE         __U32_TYPE
> -#define __OFF_T_TYPE           __SLONGWORD_TYPE
> +#define __OFF_T_TYPE           __SQUAD_TYPE
>   #define __OFF64_T_TYPE         __SQUAD_TYPE
>   #define __PID_T_TYPE           __S32_TYPE
>   #define __RLIM_T_TYPE          __ULONGWORD_TYPE
> 
> Then we could remove the __USE_FILE_OFFSET64 in stat.h and fcnt.h in
> aarch64. And truncate and ftruncate is same as truncate64 and
> ftruncate64.

I don't know what the glibc developers prefer, but I think the
result needs to be something like that: either __OFF_T_TYPE is
defined as you write above as a 64-bit type, or the user-visible
off_t typedef unconditionally uses __OFF64_T_TYPE rather than
__OFF_T_TYPE.

> Otherwise we need to handle the pad like yury do it in
> stat.h, and we need to handle the bigendian as well:

I see.

> @@ -35,12 +35,21 @@ struct stat
>     {
>       __dev_t st_dev;			/* Device.  */
>   #ifdef __ILP32__
> +
> +#if !defined(__AARCH64EB__)
>       unsigned int __st_ino_pad;
> +#endif
> +
>   # ifndef __USE_FILE_OFFSET64
>       __ino_t st_ino;			/* File serial number.	*/
>   # else
>       __ino_t __st_ino;			/* 32bit file serial number.	*/
>   # endif
> +
> +#if defined(__AARCH64EB__)
> +    unsigned int __st_ino_pad;
> +#endif
> +
>   #else

This would indeed be silly, we really don't want anyone
to access the old __st_ino field or the 32-bit version of
the offset here.

	Arnd