While this is not directly supported by Toradex one can apply the real-time patches to our i.MX6 Kernel.
In the meta-fsl-arm layer there is a recipe that applies the patches to the vanilla Freescale/NXP kernel tree. This includes addtional i.MX6 specific patches not included in the kernel.org real-time patch set.
As Toradex did backport the extcon subsystem for use with the unusual USB client/host switching on the Colibri i.MX6 the real-time patch itself fails in two hunks. Thus one has to patch the patch before applying it to the kernel tree.
To build the real-time kernel outside of OE one can follow:
Before the configuring and building steps one would patch the kernel tree.
First download and unzip the real time patch from kernel.org. Then apply the patch for rt-patch to it.
Secondly apply the patches given in the linux-imx-rt_3.14.28.bb recipe in the order given in the SRC_URI variable.
Third configure the Kernel for the wanted module and then change the configuration using whatever is needed for your real-time use case.
Then build and deploy the kernel as one would normally do
One could also put together a recipe similar to linux-imx-rt, doing the patching of the patchfile before the do_patch task and thus automating the above steps.