Messages in this thread | | | Subject | Re: streaming data from linux host to devel board | Date | Thu, 16 Dec 1999 02:22:18 +0000 (GMT) | From | Alan Cox <> |
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> I use another kernel buffer (from __get_dma_pages) in which the > software on the mediaprocessor can write data and a linux user-space > daemon can watch this buffer and parse dump it's contents. This is > used for printf and basic file IO support for mediaprocessor software.
That is probably the most efficient approach. If its PCI you dont need to pull DMA pages. You can also grab a chunk of pages if your board can do scatter gather pulls from them.
Using mmap() means you can map the same memory into the address space of the user app and the kernel. That is probably as good as you get for small stuff.
> Basically, I'm looking for a fast way for software running on our > mediaprocessor to stream in data from the host. The applications > being audio/video/imaging codecs that are running on the > mediaprocessor would get their input data from the linux host.
With 2.3.x you can use kiovecs and the routines with them to lock down user pages and get a list of addresses. So you can
foo_write
get kiovec lock pages translate addresses and send message to media processor
returning irq unlock pages return done
Alan
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