Maybe the wrong function is being used here, I'm not sure. I ran into a problem with using virt_to_phys. The acacia driver for the IDT rc32438 chip uses virt_to_phys to convert from a KSEG1 address to a physical address. Somehow this works on their 2.4.18 kernel but does not in the 2.4.22 tree. After changing virt_to_phys to this: return (unsigned long)address - KSEGX(address); everything worked just fine. I guess what I'm wondering is, is this the correct way to get a physical address for use with DMA? The note in io.h above the function says no but fails to tell me what should be used. My guess is virt_to_bus is correct but they are identical functions. Since I didn't write this driver, I can only assume that address for the rung descriptors are accessed via KSEG1 so that they are uncached and don't require flushing after each access. I had a lot of dropped packets when I failed to access the ring descriptors via KSEG1. BAPper
