Linux Extended-stat system call

[Arnd Bergmann]

On Wednesday, June 22, 2016 5:03:43 PM CEST Florian Weimer wrote:
> On 06/22/2016 04:08 PM, David Howells wrote:
> 
> > One thing I would like to do is make it so that stat() can use it with minimal
> > effort.
> 
> Why is this an important goal?
> 
> Existing architectures will keep using the old system call for the 
> legacy stat interfaces.  New architectures can use the new system call, 
> but will probably have a different definition of struct stat (which 
> might well be guided by our experience with the extended stat interface).

For the y2038 work, we have to replace the stat system call on all 32-bit
architectures (and mips64, which uses 32-bit st_mtime). We can do this
by adding just a new version of the fstatat() syscall to the kernel that
matches the ABI of the 64-bit architectures, or by mapping everything
onto the new xstat.

Adding just one new syscall entry point instead of two simplifies the
kernel implementation quite a bit, but if there are good reasons for
still providing a new fstatat version, we could do that too.

	Arnd