Re: bus_alloc_resource question

From: Chuck Tuffli (chuck_tuffli_at_agilent.com)
Date: 07/27/04

  • Next message: Jake Burkholder: "Re: bus_alloc_resource question" 
    Date: Tue, 27 Jul 2004 09:51:25 -0700
To: "M. Warner Losh" <imp@bsdimp.com>, Jake Burkholder <jake@locore.ca>

    On Mon, Jul 26, 2004 at 09:54:53PM -0600, M. Warner Losh wrote:
    ...
    > Generally, one doesn't need to set the resource value. Doing so
    > usually indicates the presence of some bug in the system. Also, just

    I realize now that the original email wasn't clear. This is a bus
    driver for a new bus. Think of the physical addresses from 0xe0000000
    - 0xefffffff as being a memory mapped config space for devices. Each
    4KB segment of this region maps the configuration space for every
    possible bus, device, function number combination. I was thinking that
    each of these segments was a bus resource, but maybe that isn't the
    right approach. Any thoughts as to a better approach?

    Jake Burkholder suggested using pmap_mapdev() for small sections of
    memory, but cautioned that this uses up virtual address space. The bus
    driver could map each segment to test if a device was there and unmap
    the segments that didn't contain devices. 

    -- 
Chuck Tuffli
Agilent Technologies, Storage Area Networking
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