Re: [gpsd-dev] Draft Stratum 1 Microserver HOWTO is up

[Hal Murray]

[I've changed some fancy single quotes to my normal ascii single quote.  
Searching for copied text may not workright.]


I think it needs an introductory paragraph with a date-stamp explaining that 
the PI-3 is new and still under active development and don't be surprised 
if/when things break.

> lithium button cell (except the SKU 424254, which is powered by an on-board 
> supercap
Their web page says:
  XH414H-IV01E backup battery for more of time keeping ...

> A micro-SD card. 1GB is minimal. 4GB is plenty.

I decided 4 GB wasn't big enough, but I build gpsd, NTPsec, and NTP classic, 
and keep lots of log files.  It felt like builds were slowing down, but maybe 
I was just getting impatient.  I don't have hard numbers.  I think SD cards 
work better if they are not close to full.


You describe assembling the board and HAT before inserting it into the case.  
Have you tried that?  I don't think it will work.  The board has to go in 
tilted, HMDI side first.  The HAT gets in the way of the tilt.

You might mention the DogBone case.


> SBC's primary or P1 GPIO

It seems unlikely that other SBCs will call that connector P1.  Maybe Pi 
clones do.


>  There's a second or P5 GPIO connector...

What board are you looking at?  I don't see it on my Pi 3.

> P5-[1-8]

Seems strange for a 2x3 array to go up to 8.

> device will likely be /dev/sdd

Mine works out to be sdd, but I think that depends on several things.  I have 
a second hard disk that gets sdb, and I use a multi-slot USB to small-card 
adapter that sets up sdc, sdd, sde, and sdf.  The SD slot just happens to be 
sdd.

> We provide a script, ddimage, to semi-automate

I think you need a few more words here.

> ssh address@hidden

That assumes your Linux box supports the client side of mDNS, or something 
like that.  It may be common on desktop setups that are trying to do 
everything for everybody but I'm not sure it is universal.

> Call sudo raspi-config on the Pi.

Up to now, you have been using $ and #.  Why shift to "call"?

> # apt-get dist-upgrade

If that gets a new kernel, you want to reboot.

> commenting out the dtoverlay and force_turbo lines.

Where did force_turbo come from?

> labeled, near the north end of the connector

On the Adafruit HAT.  Have you checked the others?

> There is a different, non-HAT Adafruit product, the "Ultimate GPS Breakout
> Board", that also uses GPIO18/P1-12. This may be a source of confusion if
> you read some of the references in this document.

The breakout board doesn't know anything about GPIO pins.  You are probably 
thinking of some writeup that cloned the Uputronics pins.

> # Known Stratum 1 servers with excellent quality and connectivity.
> server 199.102.46.72 iburst     # tock.usshc.com
> server 149.20.64.28 iburst      # clock.isc.org
> server 17.254.0.49 iburst       # tick.apple.com

This gets complicated.  It's also important.

In general, you don't want to wire a name or address into gear that you don't 
directly control without the owner's permission.  If you do get their 
permission, you want to set things up so that they can easily and cleanly 
revoke that permission.  This holds for things like anti-spam black lists as 
well as NTP servers.

One way to revoke permission is to insert a layer of indirection in the DNS, 
a cname.  Deleting that cname (or the landing name) breaks things and stops 
the traffic.  (It may shift the load to the DNS servers.)

The wikipedia page on NTP abuse is very good.
  https://en.wikipedia.org/wiki/NTP_server_misuse_and_abuse
I think Dave Plonka's writeup should be required reading for any computer 
science degree.

On top of all that, the connectivity is only good if you are located near the 
servers.

> GPS Serial data reference (NTP0) [Second one]
  NTP0 => NTP1

> Internet time servers 

There is no section of the ntp.conf labeled "Internet time servers"

Your ntp.conf doesn't enable any logging.


> # ntpsec/build/main/ntpq/ntpq -p

The printout doesn't match the ntp.conf you just described.  It's still using 
4 pool servers.

> # cp pinup /usr/local/bin
What's "pinup"?  Where did it come from?

> Install this text as the file /etc/init.d/timeservice and make it executable:
How do you expect "this text" to magically turn into a file?


> RUNASUSER=nobody
That's fine for gpsd which doesn't do any logging.
ntpd usually runs as user ntp to get access to /var/log/ntpstats
Most (many, several) distros setup /var/log/ntpstats
(I use /var/log/ntp rather than /var/log/ntpstats)
Debian has a cron job that compresses and prunes them.


> Install this text in the directory /etc/systemd/system/:

Same "this text" problem.

> can mame a link to it from

  mame => make  ??

> using adduser run as root.

I think adduser needs a few flags.  I normally forget them and have to go 
back and patch things up.

> machine to the build account

How did "me" turn into "the build account"?

> You will probably want to re-fetch clockmaker and do a
> "clockmaker --build" in your home directory.

I would reorder things so that happens naturally.  Just do the security stuff 
first.

> WiFi is deliberately not removed, in order to give you a
> fallback TCP/IP access when a cable is inconvenient.

The recipe for removing WiFi would be convenient.  Or a pointer to one.

> Configuring for a static IP address ==

Trailing ==

> wonder why this recipe uses gpsd through SHM rather than ntpd's native

Mumble.  That's worth another message.

> Edge-detection issues and new HATs

Mumble.  That's long and complicated.  I would simplify things greatly.  Drop 
the ppio detects column until we get an example that is different.

> Odroid C2

Looks like a link didn't make it.

----------

I agree with most of Gary's comments.  I only skimmed them.

----------

Typos:

On my web browser, there is a dangling period after the [There is one ...] in 
the first paragraph.
The [...] is on a separate line.  The period is alone on the next line.

> with a conventional PS and cable-attached GPS
  PS => PC

> Uputronics board snugs ino an on-board fitting
  ino => into

The References section at the bottom is missing a [CASE} in front of the 2258 
link.
Similarly, the following line has a [, but no tag or ]

> The HATs this HOWTO describes

I'm not a grammar wizard, but that's hard to read.  Maybe
  The HATs described in this HOWTO...


-- 
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