Re: [PATCH] rust: time: New module for timekeeping functions

[Thomas Gleixner]

On Tue, Feb 21 2023 at 09:13, Josh Stone wrote:

> On 2/21/23 4:32 AM, Thomas Gleixner wrote:
>> Now the problem is that 'Instant' in it's specification is bound to
>> CLOCK_MONOTONIC and there is no way to express CLOCK_BOOTTIME, but
>> that's a shortcoming of the spec which ignores CLOCK_BOOTTIME
>> completely. IOW, that's also a problem for user space.
>
> That's not exactly *specified* -- it's meant to be opaque time. It is
> documented that this currently uses clock_gettime monotonic on unix
> targets, but "Disclaimer: These system calls might change over time."
> CLOCK_MONOTONIC isn't even consistent across unix targets whether that
> counts suspended time. It's been debated if we should switch to
> CLOCK_BOOTTIME on Linux, but for now we're sticking to monotonic:

You'll need both when you want to implement substantial parts of the low
level user space stack in Rust. Same for CLOCK_TAI.

Thanks,

        tglx