On Mon, Nov 19, 2001 at 03:29:46PM -0800, Joon wrote:
I understand that it is possible to plug the eval board into the 33-MHz 32-bit PCI slot of a standard PC (after some jumper and firmware changes).
Yes, this is true.
1. Can the host PC access the SDRAM, SRAM, registers, etc on the IXP1200?
Only the SDRAM plus some PCI registers are accessible from the host PC. The SRAM, Scratch Memory, and most other registers are not accessible.
Is using the IXP1200 in the PCI slot of a PC a supported mode of operation in the first place?
It's "weakly supported." Someone from Intel can chime in here. The board jumpers allow it to be plugged into an active PCI bus. There is some documentation from Intel on how to do this. I will be posting information on the set-up we use at Princeton to get an evaluation board to work in a Linux PC. It does involve changing the Flash firmware. Look for details on this list soon.
2. Can the StrongArm initiate a DMA transfer directly between its SDRAM and PC host memory? Any idea what is the rough performance is?
Yes. I've only made a couple of measurements: IXP1200 --> Pentium DMA Push 64-byte block 13.10 MByte/sec IXP1200 --> Pentium DMA Push 1500-byte block 49.01 MByte/sec Pentium --> IXP1200 DMA Pull 64-byte block 11.47 MByte/sec Pentium --> IXP1200 DMA Pull 1500-byte block 24.66 MByte/sec I didn't do anything to make it faster.
3. Can the StrongArm generate interrupts to the host PC over the PCI bus?
Yes.
4. Can we really expand the SDRAM memory on the IXP1200 to 256MB as listed in the specs?
No. The IXP1200 chip supports upto 256MB. However the evaluation board is hardwired at 32 MByte. Scott