layout - What's the schematic to share one crystal with two micros?

How do I share a single crystal (not a complete oscillator module) between two micros? Is it OK to just connect everything as normal for the first micro and also directly connect its XO to the XI of the second microcontroller? I expect to place the micros very close together on the board.

Answer

What I have done when I needed to share a clock between micros is to have the crystal drive the oscillator on one micro and then use the oscillator output pin (typically CLKOUT or OSCOUT) from that micro to drive the second micro.

I would expect problems trying to drive two oscillators from the same crystal, if for no other reason than that the capacitance of the long PCB traces required to go between the two processors would cause a malfunction.

^{simulate this circuit – Schematic created using CircuitLab}