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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.
Arnd