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Date:      Mon, 18 Dec 2006 20:05:53 +0530
From:      <tanniru.sankar@wipro.com>
To:        <freebsd-net@freebsd.org>
Subject:   ' bus_dmamap_load_mbuf_sg ( ) ' function usage problem
Message-ID:  <8B9F8433B684734581EB519F1A3E5AF436CC6A@blr-m3-msg.wipro.com>
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Hi,
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   I am facing a problem on FreeBSD 7.0 during mapping using '
bus_dmamap_load_mbuf_sg ( ) ' function .
   Details are below.
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   It is AMD 64 bit machine. I have allocated jumbo buffer memory using
' m_getcl ' function.
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       mp =3D m_getjcl(M_DONTWAIT, MT_DATA, M_PKTHDR,  MJUM9BYTES);
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    As it got success here, I am trying to map the buffer as below.
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       err =3D bus_dmamap_load_mbuf_sg(dma_tag_rx, map, mp, &seg, &cnt,
BUS_DMA_NOWAIT);
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      Here it is getting error for the mbuf size equal to  MJUM9BYTES.
The type of error is ' EFBIG  '.
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    I have create  rx jumbo dma tag with attributes as following.
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    bus_dma_tag_create(

        NULL,                               /* Parent  */

        PAGE_SIZE,                    /* Alignment */              =20
        0,                                    /* Bounds  */

        BUS_SPACE_MAXADDR, /* Low Address  */                 =20
        BUS_SPACE_MAXADDR, /* High Address   */              =20
        NULL,                     /* Filter Function           */

        NULL,                     /* Filter Function Arguments */

        MJUM9BYTES,       /* Maximum Size              */

        1 ,                           /* Number of Segments        */

        MJUM9BYTES,       /* Maximum Segment Size      */

        BUS_DMA_ALLOCNOW,  /* Flags                     */

        NULL,              /* Lock Function             */

        NULL,              /* Lock Function Arguments   */

        dma_tag_rx)     /* DMA Tag                   */

    I have seen the myri10ge and mxge source code, they are allocating
maximum buffer size as MJUMPAGESIZE.
    is it like this is the maximum size we can dmamap??
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      could anyone  help me on this.
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Thanks,
Sankar.
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       Siva Sankar . T
           Project Engineer

      Wipro Technologies

         No.53/1 Hosur Road,=20
         Madivala,
         Bangalore- 560 068. India
         Tel:+91-80-25502001 Extn.5056=20
         Mobile:9886894429=20
         tanniru.sankar@wipro.com
         www.wipro.com

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