Is the kernel 100% reentrant?

No. It's getting there though. As of this date (12-Sep-96), some ofthe drivers are still not reentrant. What does this mean? It means thatthreads making various system calls will block other threads until thecall is completed. Will it crash? No. When will the fine-threading (nottreating system calls as a single operation) work? That's currently inthe works (the 2.1.xx goal is to get the kernel 100% reentrant).

Please note that this does not mean: avoid at all costs. It means thatas you work on your threaded code, you will not have all the performanceas you might with a fully reentrant kernel. Be patient; we're getting there.