uart vs sio differences ?

Mike Tancsa mike at
Mon Dec 8 20:49:20 UTC 2008

At 02:18 PM 12/8/2008, Marcel Moolenaar wrote:

>I see, so the FreeBSD box with uart(4) is missing data,
>not the Windows machine, right?

         Correct.  The FreeBSD box never gets the full data, nor do 
we see it on the "protocol analyzer".  Our analyzer is just a special 
serial cable that copies the data from both sides to the monitor 
program (a dos app) on another machine.

>Do you know if you get the first 30 bytes or the last 30
>bytes or some mix?

Just checked, and we get the first 31 bytes each time.  Is it 
possible the larger fifo buffer of the 16950 is holding onto the data 
too long ? The sio sees it as a plain old 16550, but the uart driver 
sees it as the 16950 that it is.


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