The Xillybus Forum

Hi Eli,

I remembered I saw this in one of your documents but I could not find it now somehow. So just to confirm, is a restart is needed every time I download the bitstream (based on xillybus) into FPGA?

Best,
Chongxi

Hello,

The host must be powered down when the FPGA is reconfigured, as a matter of fact, or anything can happen, in particular an immediate crash of the PC: The PC's hardware isn't designed to expect a sudden disappearance of a PCIe endpoint.

However quite often, the PC doesn't crash even when the FPGA is reloaded, and on Windows it's often possible to rescan the bus and pick up the newly loaded FPGA's PCIe interface (in which case the DMA buffers' memory of the previous FPGA bitstream is lost, since the driver can't shut down properly).

But the only safe way is with the PC off. So yes, a restart is required if you want to do it cleanly.

Regards,
Eli