Hi Marko,
Thanks, with the logging.properties from http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2009q3/003993.html I got some warnings about roundabouts and fixed a few already.
Good, glad it's useful to you.
I did not find the old discussion on a problematic roundabout, so I cannot check the data. I am just guessing that the problem could be that the roundabout segments were not tagged junction=roundabout (because some validator or renderer could have problems with roundabouts defined in multiple segments). That would be an error of the validator or renderer, of course.
Splitting roundabouts into segments is very common in the UK because of route relations. i.e. a bus route uses part of a roundabout and so the roundabout is split into segments so that only a portion of the roundabout is part of the bus route. You may also wish to try out the new --check-roundabout-flares option which checks that roundabout flare roads are sane (oneway, point in the right directions and don't extend further than they need to). For the GB data, enabling that test gives over 2000 warnings, the vast majority of which are real problems that either break the routing completely or at least give odd routes. I am (slowly) editing the OSM data to fix the problems. It's incredible what crap people are happy to put into the OSM database. I get the impression that most contributors don't give a toss about the map being routable or not. Cheers, Mark