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Re: [Diagnosed]: Timeservice not running on Ubuntu 16.04

From: Sanktwo
Subject: Re: [Diagnosed]: Timeservice not running on Ubuntu 16.04
Date: Sat, 6 Jun 2020 10:12:33 +0100
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.8.1

On 05/06/2020 14:34, Dan Williams wrote:
Yo Gary,

I think I've diagnosed what the problems are, but not the fix.
- User-space (plain) pps is not working, (reasons not clear)
- root-space (kernel) ppps is not working, due to something on our side.

You need to separate in your mind the difference between "kernel space versus user space" 
from "normal users versus root user".

Programs run by "root" all run in user space just like any other user programs. The difference is that they have greater privileges offered by the kernel i.e. can trash a lot more than just things owned by the user "root"

"kernel space" is reserved solely for the Linux kernel and some (most?) device drivers. Ignoring virtualisation at the moment, the only program running in kernel space is called Linux and is not a program run on behalf of a user,  root or otherwise.

For most processors kernel space is protected by hardware mechanisms where the protection between users in user space is protected by the Kernel (with hardware help of course).

gpsd is not part of the kernel and therefore can never run in Kernel space. It 
can, and does, run with root privileges in user space.

I hope that helps.

Ray - gpsd amateur

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