TL;DR: Don’t waste your time like we did – 1394 boot debugging no longer works on the latest builds on Windows 10.
As you might already be aware, native 1394 kernel debug support was pulled from the latest Windows 10 releases. An officially sanctioned workaround was provided by the kernel debugging team at Microsoft and we mostly considered this to be a minor bump in the road.
Unfortunately, we had a surprise this week when we installed some new test machines running 1703 and were unable to perform boot debugging over 1394 (bcdedit /bootdebug on). After a bit of investigation we discovered that the 1394 bits have been entirely removed from the boot loader. Thus, from this point on it is impossible to boot debug over 1394. The workaround provided in the previous link only applies to “standard” kernel debugging.
We love 1394 debugging and are sad to see the reduction in functionality. I seriously doubt we’ll see a reversal of this decision, but we can always dream!