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Re: Allocating Qbus memory space and Qbus map space



> On Jun 15, 2015, at 5:11 PM, Charles Dickman <chd%chdickman.com@localhost> wrote:
> 
> On Fri, Jun 12, 2015 at 10:55 PM, Matt Thomas <matt%3am-software.com@localhost> wrote:
>> 
>>> On Jun 12, 2015, at 7:29 PM, Charles Dickman <chd%chdickman.com@localhost> wrote:
>>> 
>>> I can't find how the kernel handles allocation of Qbus memory space.
>>> 
> 
>> 
>> There should be an extent for the Q-bus memory in bus_dma_tag_t for
>> that q-bus (_sgmap->aps_ex).
>> 
>> Use it with
>> 
>> extent_alloc_region(dmat->_sgmap->aps_ex, vastart, vaend, EX_WAITOK);
> 
> OK That's what I did.
> 
>> Thinking about this, bus_space_map on the iot should allocate the same
>> address region from the sgmap.  That it does not is a bug.
> 
> Then what I was looking for wasn't there but should be.
> 
>> Or the uba attach code should probe each page and if does
>> not timeout, mark it as mappable.
> 
> Am I correct that now there are two extents that are covering the same
> resource, but they are not coordinated? bus_space_map covers the Q22
> address space including the I/O space. dmat->_sqmap->aps_ex covers the
> Qbus map. Properly done, the uba bus_space should only include the
> memory that exists in real devices and the rest of the address space
> given to the DMA map.

Correct.


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