[yocto] Problems building core-minimal-rt on Jethro (2.0.1) and Krogoth (2.1)

[Ronald Oakes]

My project will need to be real-time (we're probably putting a crystal
controlled clock in), so I'd like to have the real-time kernel.  So,
I've been attempting to build core-minimal-rt on both 2.0.1 and 2.1.
I get errors on both, albeit different errors.

Jethro:

On 2.0.1, the do-patch for linux-yocto-rt-* fails, ultimately with the
message: "Your branch is behind 'origin/standard/preempt-rt/base' by
691 commits, and can be fast-forwarded." followed by "(use "git pull"
to update your local branch)"

I get this error on all distros, including poky-bleeding.  I've not
been successful in disabling the mirrors just for linux-yocto-rt.  I
am now trying a build, albeit on my slow machine (two cores, where if
I don't force bitbake into running one task at a time, it hangs),
after deleting everything except the conf directory to see if that
makes any difference

Krogoth:

On 2.1, the error message occurs very quickly:

ERROR: Nothing PROVIDES 'linux-yocto-rt' (but
/home/ron/yocto_2.1/poky/meta/recipes-rt/images/core-image-rt.bb
DEPENDS on or otherwise requires it)
ERROR: linux-yocto-rt was skipped: PREFERRED_PROVIDER_virtual/kernel
set to linux-yocto, not linux-yocto-rt
ERROR: linux-yocto-rt was skipped: PREFERRED_PROVIDER_virtual/kernel
set to linux-yocto, not linux-yocto-rt
NOTE: Target 'linux-yocto-rt' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['linux-yocto-rt']
NOTE: Target 'core-image-rt' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['core-image-rt', 'linux-yocto-rt']
ERROR: Required build target 'core-image-rt' has no buildable providers.
Missing or unbuildable dependency chain was: ['core-image-rt', 'linux-yocto-rt']

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Any clues as how to work around either?

Ron Oakes