+++ This PCR was initially created as a clone of PCR #7994 +++

This limitation only applies to the x86 architecture.  If a thread
loads the DS (data segment) register, and before any other instruction
references the data segment a floating point instruction is executed
that triggers a deferred floating point context switch the kernel will
halt.  Note that most instructions that reference memory implicitly
reference the data segment.  Compiler generated code does not set
segment registers.

Analysis:

The FP and SIMD floating point context switch IDT raw handlers do not
set the data segment register prior to executing instructions that
implicitly reference the data segment register.  On a trap into the
kernel, the interrupt/exception management hardware sets the stack
segment selector, but not the data segment selectors.  Kernel DDD
requirement DDD_DEOS_X86CPU_110 requires that all traps reload the DS
register.  The other IDT raw handlers (exception, interrupt, and
rawServicesTrapHandler all set all the segment registers, but that
requirement was missed when implementing the deferred floating point
context switch raw handlers. 

Workaround:

Because the compiler does not inject code that updates the DS register it is simplest to ensure code does not modify the DS register.  The following instructions can update the DS register:
 - lds
 - mov 
 - pop

The following bash command can be used to check if an executable, shared library, or dll modifies the DS register.

objdump -d kernel.exe | grep -e "\(mov .*%ds\)\|\(pop.*ds\)\|\(lds \)"

If a file that updates the DS register is found the next step is to ensure that there is an instruction that accesses (reads or writes) the data segment prior to any floating point instruction.