Re: [PATCH 6/7] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature

Alan Cox
2018-01-04T18:53:05Z

On Thu, 4 Jan 2018 09:56:47 -0800
Tim Chen <tim.c.chen@linux.intel.com> wrote:

> There are 2 ways to control IBRS
>
> 1. At boot time
> noibrs kernel boot parameter will disable IBRS usage
>
> Otherwise if the above parameters are not specified, the system
> will enable ibrs and ibpb usage if the cpu supports it.
>
> 2. At run time
> echo 0 > /sys/kernel/debug/ibrs_enabled will turn off IBRS
> echo 1 > /sys/kernel/debug/ibrs_enabled will turn on IBRS in kernel
> echo 2 > /sys/kernel/debug/ibrs_enabled will turn on IBRS in both userspace and kernel
>
> The implementation was updated with input from Andrea Arcangeli.
>

Why are these under debug ? This isn't a debugging thing.

Alan