On Tue, Oct 10, 2017 at 07:38:37PM +0100, Dave P Martin wrote: > This patch adds two arm64-specific prctls, to permit userspace to > control its vector length: > > * PR_SVE_SET_VL: set the thread's SVE vector length and vector > length inheritance mode. > > * PR_SVE_GET_VL: get the same information. > > Although these calls shadow instruction set features in the SVE > architecture, these prctls provide additional control: the vector > length inheritance mode is Linux-specific and nothing to do with > the architecture, and the architecture does not permit EL0 to set > its own vector length directly. Both can be used in portable tools > without requiring the use of SVE instructions. > > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> > Cc: Alex Bennée <alex.bennee@xxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
