From: Subrata Modak <subrata@linux.vnet.ibm.com>
To: fmhess@users.sourceforge.net
Cc: sachinp@linux.vnet.ibm.com, sfr@canb.auug.org.au,
Greg KH <greg@kroah.com>,
linux-kernel@vger.kernel.org, Linuxppc-dev@ozlabs.org,
Ian Abbott <abbotti@mev.co.uk>,
linux-next@vger.kernel.org, paulus@samba.org,
Geert.Uytterhoeven@sonycom.com, geert@linux-m68k.org,
David Miller <davem@davemloft.net>
Subject: Re: [BUILD FAILURE 01/04] Next June 04:PPC64 randconfig [drivers/staging/comedi/drivers.o]
Date: Sun, 07 Jun 2009 20:06:45 +0530 [thread overview]
Message-ID: <1244385405.5265.7.camel@subratamodak.linux.ibm.com> (raw)
In-Reply-To: <200906060936.22322.fmhess@speakeasy.net>
On Sat, 2009-06-06 at 09:36 -0400, Frank Mori Hess wrote:
> On Saturday 06 June 2009, Greg KH wrote:
> > Frank and Ian, any thoughts about the vmap call in the
> > comedi_buf_alloc() call? Why is it using PAGE_KERNEL_NOCACHE, and what
> > is the prealloc_buf buffer used for?
>
> It is a circular buffer used to hold data streaming either to or from a
> board (for example when producing an analog output waveform). Reads and
> writes to the device files read/write to the circular buffer, plus a few
> drivers do dma directly to/from it. I personally don't have a problem
> with requiring drivers to have their own dma buffers and making them copy
> data between their private dma buffers and the main circular buffer. I
> guess the original design wanted to support zero-copy dma.
Great to hear that. How about a patch that solves my build problem on
PPC64(the problem seems to be existing for long) ?
Regards--
Subrata
>
next prev parent reply other threads:[~2009-06-07 14:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-05 18:26 [BUILD FAILURE 01/04] Next June 04:PPC64 randconfig [drivers/staging/comedi/drivers.o] Subrata Modak
2009-06-05 18:26 ` Greg KH
2009-06-05 23:31 ` Benjamin Herrenschmidt
2009-06-05 23:32 ` Benjamin Herrenschmidt
2009-06-06 0:56 ` David Miller
2009-06-06 4:16 ` Benjamin Herrenschmidt
2009-06-06 5:51 ` Greg KH
2009-06-06 13:36 ` Frank Mori Hess
2009-06-07 14:36 ` Subrata Modak [this message]
2009-06-09 3:50 ` Benjamin Herrenschmidt
2009-06-09 18:34 ` Subrata Modak
2009-06-09 18:54 ` Geert Uytterhoeven
2009-06-09 22:34 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2009-06-04 13:31 Subrata Modak
2009-06-04 18:07 ` Greg KH
2009-06-04 20:40 ` Geert Uytterhoeven
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