Comment 15 for bug 1156138

On 24/07/13 19:00, Stephen Parry wrote:
> Dug deeper, got more answers, but also more questions: rcupdate.h is heavily conditional on PREEMPT causing __rcu_read_lock/unlock to be extern rather than inline.
> However, this leaves the most fundamental question of all: why are some functions OK to call from non-GPL code but others not? should these functions be marked as OK to call?

Thanks very much for your efforts, Stephen. I won't have time to catch
up with your very useful research this week. However, I am still very
interested in a solution and your approach seems more productive than
building a custom low-latency kernel and hoping the driver will compile.

Still, given the earlier reports, I wonder which of the many hundreds of
kernel build options were defaulted to "something that works", rather
than the set of options in the standard ubuntu low-latency build
("something that doesn't work")? These two build paths must be
generating different kernel header files, mustn't they?

Sorry to be lazy (MUST get back to work!), but has this problem been
reported against low-latency kernels for other distros? The answer might
provide a valuable diff of kernel build options.

Brian