Re: SRAM Based FPGA Devices

[Michael Richardson <mcr@solidum.com>]

>>>>> "Dominick" == Dominick Cafarelli <dominick_cafarelli@flashcom.net> writes:
    Dominick> loading, the soft loadable FPGA (which contains a PCI core)
    Dominick> will now have its PCI configuration registers appear on the PCI
    Dominick> bus.
  
  Understood.

    Dominick> I am wondering if any one has implemented such a device.  We
    Dominick> need to support this type of adapter in Windows NT 4.0.  This
    Dominick> adapter is a Network card and thus an NDIS Miniport driver will
    Dominick> be developed.  Will the NDIS driver in Windows NT 4.0 be able
    Dominick> to recognize this softloadable FPGA after it has been loaded?

  Nope. The hangup is that you can't get the "BIOS" to allocate you a
physical address. I think that this is a major limitation of PC BIOSs, and
I don't know how they will ever support Hot Insertion. Maybe there are
extensions, but I haven't seen them yet. 
  I posted about this a month ago.

    Dominick> I am a bit concerned because the BIOS will not see that FPGA
    Dominick> because it is essentially invisiable during BIOS loading.
    Dominick> Given that the BIOS has the responsibility of allocating the
    Dominick> actual base addresses of all the PCI devices, when this FPGA
    Dominick> device appears, it will not be programmed with the appropriate
    Dominick> base address.

    Dominick> Can someone help!

  Put a serial EEPROM on your board, and connect it to your programming
pins. Have a minimal load in the EEPROM that loads the soft PCI core. You can
reprogram the device later if you need to. For development purposes, you can
just make sure that a soft reset doesn't erase the FPGA and do a reboot after
reprogramming. That isn't acceptable for end-users though.

  We have the same problem with a Lucent OR3TP12 device. It has a hard PCI
core and FPGA logic which is loadable via PCI configuration space, but the
BARs are not set up until the FPGA is loaded.

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