The quick answer is that it's off by default in the GENERIC config.

Somewhere we need to distinguish between features turned off because they've
been found unsafe (or are not complete yet), versus those that are turned off
just because they cause problems in a small percentage of cases, but that
should likely be turned on in a non-GENERIC kernel.

Also, it would appear among respondents so far, that I am the only one with
ESP200 (Fast SCSI) controllers. These appear internally in the SPARC Classic
and LX (and later models), and also on the FSBE/S card.

I've turned on sync & {,re}select for my build system (and no explosions so
far), but it only has one disk (fast, yes, but no possible SCSI bus contention)
so it's not what I would call a good test. I'm about to do it to my main house
server, and then to cesium.clock.org.

I'm going to start playing with ccd next...

	Erik E. Fair    fair@clock.org