On Fri, Dec 21, 2001 at 01:44:52PM -0500, Jim Paris wrote: > > Interesting - I'd not considered that. Is ISA and non ISA space seperate on > > MIPS or is it all rather ambiguous ? > > On my particular machine, system RAM is at 0x00000000, and ISA I/O > memory is at 0x10000000. The driver I'm currently trying to work with > calls check_mem_region with ISA addresses, which of course breaks when > ISA memory isn't at zero. One suggestion was to patch the driver to > use something like > > check_mem_region(virt_to_phys(ioremap(ISA_address)), ...) > > which might be the best way for now? I agree with Geert and think isa_xxx_mem_region is a better approach. Unfortunately, this requires a change in both dirver and arch-specific part. > I think a more generic way to > abstract away a bus (and support multiple types and numbers of I/O > busses) is really necessary though. Some way to register a bus with > the kernel, and bind particular busses to particular instances of > drivers, or something. > I have talked with somebody before about the address apace idea, which is rather similar to what you are talking : 1. each address space has an id. 2. kernel pre-defines a couple of well-known ones, 0 for CPU physical, 1 for virtual, etc. 3. When drivers discover the devices, they get the address and also the address space id where the address resides. 4. there are a set of macro's that converts/maps an address or an address region from one space to another. This generalized form allows multiple-PCI buses to use substractive decoding. Also removes the 1:1 mapping requirement between PCI memory space and CPU physical address space. However, the detailed implementation can be hairy, which is why it is still an idea. :-) Jun
