Hi, This implements the kernel part of IEEE Std 754 NaN interlinking support, as per "MIPS ABI Extension for IEEE Std 754 Non-Compliant Interlinking" <https://dmz-portal.mips.com/wiki/MIPS_ABI_-_NaN_Interlinking>. Four patches are included: a pair of preparatory changes, a generic one to allow ports to provide their own auxiliary vector's AT_FLAGS entry initialiser and one factoring out pieces of FP context maintenance code, respectively, and then a pair of actual changes, implementing the NaN interlinking feature proper and a prctl(2) interface to switch the compliance mode dynamically respectively. These patches rely on 2008-NaN support, recently posted, having been applied first. At this point this is a request for comments only rather than an actual patch submission for inclusion, as consensus about the specification has to be reached first. All feedback is welcome on the implementation and I'll be happy to address any questions, comments or concerns. Maciej