The different realtime kernels

[Ronan Jouchet]

Hello everybody,

Many are confused about the various realtime kernels, so here is a 
reminder of the situation as of Sept. 2010 (but _please_ see 
https://help.ubuntu.com/community/UbuntuStudio/RealTimeKernel , which is 
more detailed and continuously updated).

***Summary***
vanilla = unpatched kernel straight from kernel.org
generic = vanilla + ubuntu sauce (it's the default ubuntu kernel)

The *soft realtime kernels, prepared by changing build-time parameters*
     preempt = generic + mild configuration to reduce latency
     lowlatency = generic + aggressive configuration to reduce latency

The *hard realtime kernels, prepared by applying a big patch* from Ingo 
Molnar to the kernel source before building:
     realtime = vanilla + patch (hard to maintain and stabilize because 
merging 2 pieces of code is never easy)
     rt = generic + patch (even harder to maintain and stabilize because 
merging 3 pieces of code is harder than 2)

***Availability***
- for Maverick, generic will be the only kernel in the archives, thus 
the default kernel for ubuntu and ubuntustudio, but Alessio has been 
maintaining a PPA providing lowlatency and realtime
- for Natty or later: work is being done to include lowlatency in the 
official archives and make it the default ubuntustudio kernel

I hope this clears some doubts. By the way, this confusion is only going 
to get more intense at release time (less informed / technical users). 
Could we include some kind of note informing users about this? Why not a 
"RealTime kernel help" item in the Audio Production menu, redirecting to 
the wiki page?

Good day,

-- Ronan Jouchet