Subject: Re: bus_dmamap_sync not enough ?
To: Stephan Uphoff <firstname.lastname@example.org>
From: Jason R Thorpe <email@example.com>
Date: 02/10/2003 22:59:31
On Tue, Feb 11, 2003 at 12:54:03AM -0500, Stephan Uphoff wrote:
> bus_dmamap_sync not enough for some devices ?
bus_dmamap_sync is supposed to also provide any necessary memory barriers.
From the bus_dma(9) manual page:
On platforms which implement reordered stores, bus_dmamap_sync()
will always cause the store buffer to be flushed.
The wording might not be the best, there, but I think the intent is clear
(particularly because of the use of the word "reordered").
-- Jason R. Thorpe <firstname.lastname@example.org>