Re: API change for bus_dma

From: Andrew Gallatin (gallatin_at_cs.duke.edu)
Date: 06/27/03

  • Next message: Scott Long: "Re: API change for bus_dma" 
    Date: Fri, 27 Jun 2003 15:33:14 -0400 (EDT)
To: Scott Long <scott_long@btc.adaptec.com>

    Scott Long writes:
    > All,
    >
    > As I work towards locking down storage drivers, I'm also preening their
    > use of busdma. A common theme among them is a misuse of
    > bus_dmamap_load() and the associated callback mechanism. For most, the

    Why not just add a way to avoid deferring the callback entirely? I'm
    talking about something like Solaris' ability to pass DDI_DMA_DONTWAIT
    as the callback function to ddi_dma_buf_bind_handle().

    My desire is to know immediately whether the DMA mapping failed. If
    it failed, that's OK with me. Since my driver locks users memory and maps
    it for DMA for a potentially unbounded amount of time, I want to
    know about a failure right away, not pile up requests that will never
    be satisfied.

    Can I get the behaviour I'm after by adding BUS_DMA_NOWAIT to the
    flags I pass to bus_dmamap_load()?

    Drew

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