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Re: [Discuss-gnuradio] proposed change to ugen to enable USRP to work we

From: Daniel O'Connor
Subject: Re: [Discuss-gnuradio] proposed change to ugen to enable USRP to work well on NetBSD
Date: Thu, 4 May 2006 11:58:34 +0930
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On Thursday 04 May 2006 03:30, Greg Troxel wrote:
> Joanne has written a proposal to modify NetBSD's ugen(4) to get good
> performance for the USRP.  We'd like feedback about the technical
> approach.  (Once we have it working, the changes will be commited to
> NetBSD-current.)
> http://acert.ir.bbn.com/downloads/adroit/NetBSD-USB-continuous.pdf

I think the ioctl would be the cleanest approach - it would not break any 
existing software.

I wonder if it may be possible to have the ioctl specify a packet size and the 
kernel will keep reading data of that packet size into the buffer as long as 
it isn't full. I think that would give you something that looks a lot closer 
to a normal device (normal being "what the unix IO model expects" :)

It would be nice if you could do a readv() and then poll/kqueue/select/signal 
to see when an iovec has been filled, however I suspect that would require 
severe modification of the kernel internals.

Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
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