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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,
 
   I am facing a problem on FreeBSD 7.0 during mapping using '
bus_dmamap_load_mbuf_sg ( ) ' function .
   Details are below.
 
   It is AMD 64 bit machine. I have allocated jumbo buffer memory using
' m_getcl ' function.
 
       mp = m_getjcl(M_DONTWAIT, MT_DATA, M_PKTHDR,  MJUM9BYTES);
 
    As it got success here, I am trying to map the buffer as below.
        
       err = bus_dmamap_load_mbuf_sg(dma_tag_rx, map, mp, &seg, &cnt,
BUS_DMA_NOWAIT);
        
      Here it is getting error for the mbuf size equal to  MJUM9BYTES.
The type of error is ' EFBIG  '.
   
    I have create  rx jumbo dma tag with attributes as following.
 
    bus_dma_tag_create(

        NULL,                               /* Parent  */

        PAGE_SIZE,                    /* Alignment */               
        0,                                    /* Bounds  */

        BUS_SPACE_MAXADDR, /* Low Address  */                  
        BUS_SPACE_MAXADDR, /* High Address   */               
        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??
 
      could anyone  help me on this.
 
 
Thanks,
Sankar.
 
 
 
   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
              

       Siva Sankar . T
           Project Engineer

      Wipro Technologies

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

 



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