Date: Fri, 29 Dec 2006 12:13:08 +0530 From: <tanniru.sankar@wipro.com> To: <gurney_j@resnet.uoregon.edu> Cc: freebsd-net@freebsd.org Subject: RE: ' bus_dmamap_load_mbuf_sg ( ) ' function usage problem Message-ID: <8B9F8433B684734581EB519F1A3E5AF43D88A5@blr-m3-msg.wipro.com>
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Hi Mark,
Is it possible to allocate contigous memory of MJUM9BYTES ( 9K )
and dmamap_load in one segment ?=20
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Thanks,
Sankar
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-----Original Message-----
From: John-Mark Gurney [mailto:gurney_j@resnet.uoregon.edu]=20
Sent: Tuesday, December 19, 2006 2:19 AM
To: Tanniru Sankar (WT01 - Computing Systems & Storage)
Cc: freebsd-net@freebsd.org
Subject: Re: ' bus_dmamap_load_mbuf_sg ( ) ' function usage problem
tanniru.sankar@wipro.com wrote this message on Mon, Dec 18, 2006 at
20:05 +0530:
> I am facing a problem on FreeBSD 7.0 during mapping using '
> bus_dmamap_load_mbuf_sg ( ) ' function .
> Details are below.
> =20
> It is AMD 64 bit machine. I have allocated jumbo buffer memory=20
> using ' m_getcl ' function.
> =20
> mp =3D m_getjcl(M_DONTWAIT, MT_DATA, M_PKTHDR, MJUM9BYTES);
> =20
> As it got success here, I am trying to map the buffer as below.
> =20
> err =3D bus_dmamap_load_mbuf_sg(dma_tag_rx, map, mp, &seg, &cnt,=20
> BUS_DMA_NOWAIT);
> =20
> Here it is getting error for the mbuf size equal to MJUM9BYTES.
> The type of error is ' EFBIG '.
> =20
> I have create rx jumbo dma tag with attributes as following.
[...]
> MJUM9BYTES, /* Maximum Size */
>=20
> 1 , /* Number of Segments */
>=20
> MJUM9BYTES, /* Maximum Segment Size */
This is probably the problem... Most likely the buffer is
non-contiguous in memory, and needs 3 segments to satisfy the mapping...
Try increasing the number of segments and see what happens...
--=20
John-Mark Gurney Voice: +1 415 225 5579
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