[mkgmap-dev] Really Serious bug when not using --route

Sun May 23 19:22:55 BST 2010

On 23.05.2010 18:24, Felix Hartmann wrote:
> There is a serious bug that breaks routable maps when --route is NOT 
> given. This bug will in future break routing on most GPS devices and 
> is already inflicting Mapsource 6.16.1 and Basecamp 3.
> This means that also if you compile maps that are not routable, you 
> have to pass the --route parameter. Else the GPS / Mapsource looks 
> into an empty NOD table and may crash. This will happen as soon as you 
> mix routable maps with the non routable mkgmap created maps.
>
> The problem is that Mapsource and the GPS search for 63440000.NOD data 
> (63440000 as an example placeholder for the mapname). "Falagar", a 
> developer at Garmin said to release a fix for this bug in Mapsource 
> 6.16.2 however mentioned that this fix will not be carried on to GPS 
> devices and will still mean a deterioration of overall routing.
>
> I'm not sure what the exact problem for this is (I just tried even 
> very old mkgmap versions like 858 and also there the problem arises) 
> but currently this means that --route should be the compulsory for all 
> map creation, also not routable ones. If you have old maps (eg 
> transparent contourline maps) that are troublesome to rebuilt, then 
> opening with gpsmapedit, saving as mp and recompiling passing --route 
> parameter is enough to solve the problem.
>
> I think that until the bug is found, mkgmap should adopt --route as 
> standard, because it may happen that if users put an mkgmap created 
> without --route onto their GPS besides other routable maps, these maps 
> might impact autorouting for the other routable maps (except if 
> "deactivated" on the GPS).
Just as an update. I got the following answer from Falagar, concerning 
creating all maps with --route parameter:

/Naja, das ist halt nur ein Trick. Am besten waere es, die NOD-Flag zu 
entfernen, aber ich weiss nicht, ob ihr wisst, wo die ist. Ich weiss es 
leider auch nicht.
Es koennte evtl. ein wenig langsamer sein, wenn MS & Geraet die 
Routinginformationen erst oeffnen muessen, bevor wir feststellen, dass 
da keine Info drin ist.
Aber ich denke, das sollte erst einmal funktionieren. /

Translation. This is only a trick. Best would be to completly remove the 
NOD-Flag, but I don't know whether you know where it is. Actually, I 
don't know it either.
Eventually it could be a little bit slower if Mapsource & GPS first has 
to open the routing information, until it notices that there is no info 
inside.
But I think this would do if for a beginning.

So either someone finds the NOD flag (gmaptool also knows nothing about 
it, removing NOD data with gmaptool does not clear the NOD flag, ) and 
it will be deactivated when --route is not given, or we pass --route as 
mandatory, as we obviously miss something in the implementation. I will 
give some really old versions a go to see if they did it correctly and 
the bug got introduced with the advent of routing in mkgmap, and send a 
message if they worked correctly. If not then we probably set this flag 
since the beginning (but until recently this was no problem).
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