This is the mail archive of the mailing list for the glibc project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH 2/2] [AARCH64] ILP32: stat syscalls

On Friday, September 9, 2016 6:49:59 PM CEST Yury Norov wrote:
> Implementation details:
>  - struct stat, stat64, statfs, statfs64 layouts are taken from
>    sysdeps/unix/sysv/linux/aarch64/bits.

I was confused by the description for a moment. To clarify: 
the layout is added in that directory, not taken from an
existing file there.

>  - struct stat has broken st_ino field (legacy from arm32), so it's
>    handled in corresponding header in a way to make this structure
>    identical to struct stat64.

I think this is best, yes.

>  - statfs{,64} is identical to lp64, so corresponding syscalls are
>    wired to lp64 handlers in kernel, and implemented in custom files in
>    glibc.

During the discussion about stat64, we didn't really get to talk
about statfs64. I didn't expect to see an override here but simply
use the standard definition from
sysdeps/unix/sysv/linux/generic/bits/statfs.h or
sysdeps/unix/sysv/linux/bits/statfs.h together with the 32-bit
syscall emulation in the kernel, as we do for almost all other
syscalls now.

What's the motivation for using the aarch64 structure layout
in this case?

>  - XSTAT_IS_XSTAT64 is defined to use the same implementations for
>    syscalls.
>  - STAT_IS_KERNEL_STAT is defined, and _STAT_VER is defined to
>    _STAT_VER_KERNEL for ilp32 to bypass __xstat_conv().

Sounds good.

>  - __NR_stat, __NR_fstat, __NR_newfstatat and __NR_lstat are redefined
>    to symbols that linux exports.

Why is this in the architecture specific part? Isn't this the same
as all "generic" architectures now?

> diff --git a/sysdeps/unix/sysv/linux/aarch64/ilp32/fxstat.c b/sysdeps/unix/sysv/linux/aarch64/ilp32/fxstat.c
> new file mode 100644
> index 0000000..6fa13ad
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/aarch64/ilp32/fxstat.c
> @@ -0,0 +1 @@
> +#include <sysdeps/unix/sysv/linux/fxstat.c>

Why not sysdeps/unix/sysv/linux/generic/xstat.c ?

Same question for the other xstat files.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]