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Date:      Wed, 1 Dec 1999 16:25:22 -0500 (EST)
From:      Zhihui Zhang <zzhang@cs.binghamton.edu>
To:        freebsd-hackers@freebsd.org
Subject:   memory-to-memory copy
Message-ID:  <Pine.GSO.3.96.991201161752.5996A-100000@sol.cs.binghamton.edu>

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I used to know that memory to memory copy is done by the DMA controller in
the I/O bridge (Actually, this knowledge confues me because DMA controller
normally does not store the data that pass through it.  Now the source and
destination are both memory, how can it achieve this at the same time with
one memory bus?).  I was also told that the function bcopy() is used to
setup DMA.  Now I look at the bcopy() function in i386/support.s, I only
see instructions like "rep movsb".  So how is the memory-to-memory copy
done in FreeBSD? 

Any help is appreciated.

-Zhihui



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