Re: [Fwd: Re: use of bus_dmamap_sync]

From: Dinesh Nair (dinesh_at_alphaque.com)
Date: 10/26/05

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    Date: Thu, 27 Oct 2005 00:06:48 +0800
To: Scott Long <scottl@samsco.org>

    On 10/26/05 23:54 Scott Long said the following:
    > The value of the map is an implementation detail, which is why it's an
    > opaque typedef. Portable code should always assume that the map has
    > valid data. Now, specifically for i386, if you have a device with a

    right, so for portability's sake, bus_dmamap_sync should be used anyway.

    > twe), and you are not using PAE, then yes the map will be NULL and the
    > syncs will do nothing. Assuming that all three of these cases are false
    > is not good, though.

    well, they are in my situation, so obviously bus dma is not the cause of
    the problem i'm seeing.

    thanx to both scottl and jhb for the explanation. this throws a lot of
    light onto the handling of dma access to devices for me. 

    -- 
Regards,                           /\_/\   "All dogs go to heaven."
dinesh@alphaque.com                (0 0)    http://www.alphaque.com/
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