Andrew Gallatin wrote: > Me too. I was about to just change it for alpha, but then I wondered > if there was a reason for having BUS_SPACE_MAXSIZE < MAXPHYS.
>From what I understand, the Alpha is limited to doing transfers in the first 2G of memory. I'm not sure if the ISA 16M memory limit is in there anywhere, either. The problem is that a DMA initiated by a bus mastering device can only access as many bis of address space as are passed through the bus, end-to-end. For ISA, this ends up being a 16M limit; I think the 2G limit on Alpha is because the limit is 32 bits, but there is some signed math that should be unsigned. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-current" in the body of the message
