kernel type naming and package version conflicts

[Darren Hart <dvhart@linux.intel.com>]

I believe I've identified why my preempt_rt kernel recipes are failing 
to build. The do_package_write_ipk is complaining about invalid 
characters in the file name - specifically:

kernel-2.6.34.7-rt-yocto-preempt_rt
*** Error: Package name  contains illegal characters, (other than 
[a-z0-9.+-])

Note the "_" in preempt_rt.

This name appears to be generated in part from the following assignment:

LINUX_KERNEL_TYPE = "preempt_rt"
LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"

Changing this to the following allows the build to succeed without error 
(replacing _ with -).
LINUX_VERSION_EXTENSION ?= "-yocto-preempt-rt"

As I see it we have two options, we can rewrite linux-yocto kernel 
branches for use in bitbake package names (replacing _ with -), or we 
can forbid the use of _ in the linux-yocto git branches. Rather than 
clutter up the recipes with string manipulators, I would prefer the 
latter option.

Bruce, Tom, do you have an opinion?


-- 
Darren Hart
Yocto Linux Kernel