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 > -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
