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Date:      Fri, 15 Nov 2002 10:36:18 -0600 (CST)
From:      mark tinguely <tinguely@web.cs.ndsu.nodak.edu>
To:        chuck_tuffli@agilent.com, freebsd-hackers@FreeBSD.ORG
Subject:   Re: bus_dmamem_alloc failing
Message-ID:  <200211151636.gAFGaIP16259@web.cs.ndsu.nodak.edu>
In-Reply-To: <20021115141048.GA367@thegrail.rose.agilent.com>

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since the allocated space is larger that a physical page (65536 > 4096),
bus_dmamem_alloc() allocates physical contiguous memory. After repeated
allocations and frees, the physical memory pages will fragment and the
allocation will fail.

You may need to rethink your allocation strategy, such as
 hold some memory allocations static between unloads and loads
 if your device can take non-physical contiguous memory chunks,
  use another allocation technique
 or other imaginative tricks.

--Mark Tinguely.

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