[OpenAFS-devel] Making supergroups default to on

[Jason Edgecombe]

On 12/28/2012 03:33 PM, Simon Wilkinson wrote:
> On 28 Dec 2012, at 19:20, Andrew Deason wrote:
>> I'm not sure if that's really an absolute requirement, though. The 'code
>> quality issues' that I remember were just the opinions of a few people
>> that would make them uneasy about turning it on. I don't recall anyone
>> trying very hard to get the default changed, so maybe that's all it
>> takes.
> There were/are a number of different issues in the supergroups code. There are aliasing issues throughout, some of which could be easily fixed by inserting memcpy's rather than just using casts/assignments, but there are others that require far more in depth analysis. This second set of aliasing problems are mainly confined to the caching code, rather than the supergroups code itself. It would certainly be possible to either disable caching, or rework that code, whilst having the ubik database format remain unchanged.
>
> The other major issue is that there is bit twiddling in the caching code which makes assumptions about endianness, and about word size. I think we have now caught all of these problems - but certainly with the 1.4 series you couldn't safely run supergroups on a 64 bit machine.
>
That's slightly unsettling. We're running supergroups-enabled cell 
servers on 64bit RHEL5, albeit with YFS modifications.

My main desire is to reduce the number of conditional features to reduce 
code rot and extra ongoing development/testing efforts.

Jason