If I remember correctly, loading means that the pages become mapped
and= visible to the devices. Some buses can access only a limited
address space= , like ISA has only a 24-bit address. When a map gets
loaded, for any pages= outside of this range the temporary in-ramge
pages are allocated and the d= ata gets moved through them. On some
machines, like I think DEC Alpha, the = physicall addresses seen by
the devices are not the same as seen by the CPU= , these need to be
translated. And so on.
I think my real old articl= e had some of these explanations but now
the Daemonnews site seems to be re= al slow:
http://ezine.daemonnews.org/200008/isa.html
-SB
(sorry a= bout top quoting, it's the only kind the web interface of my
provider suppo= rts)
Feb 1, 2009 03:38:27 PM, [1]bsd.qu...@googlemail.com = wrote:
= Hi,
at first the cut of text from man (9) bus_dma:
bus_dmamap_t
= A machine-dependent opaque type describing an individual
mapp= ing.
One map is used for each memory allocation that will b= e loaded.
Maps can be reused once they have been unloaded..= .
Question: What exactly means "Loading of memory allocation" in thi s
context
?
Could anyone explain it or give me some little example wi= th DMA
functions
for understanding it.
References
1.
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