Re: [PATCH 01/23] all: syscall wrappers: add documentation

From: Arnd Bergmann
Date: Wed May 25 2016 - 17:02:26 EST

On Wednesday, May 25, 2016 1:50:39 PM CEST David Miller wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
> Date: Wed, 25 May 2016 22:47:33 +0200
> > If we use the normal calling conventions, we could remove these overrides
> > along with the respective special-case handling in glibc. None of them
> > look particularly performance-sensitive, but I could be wrong there.
> You could set the lowest bit in the system call entry pointer to indicate
> the upper-half clears should be elided.

Right, but that would introduce an extra conditional branch in the syscall
hotpath, and likely eliminate the gains from passing the loff_t arguments
in a single register instead of a pair.