On Mon, Apr 24, 2000 at 02:42:09PM -0500, Jim King wrote:
>
> One thing I've done in the past to overcome serial port problems is to patch
> sys/isa/sio.c to set the FIFO receive trigger level to 8 bytes instead of 14
> (FIFO_RX_MEDH instead of FIFO_RX_HIGH). If you have a piece of hardware or
> a misbehaved driver that's causing high interrupt latency this change be
> really beneficial, and greatly outweighs the higher interrupt overhead when
> using an 8 byte trigger.
>
> <soapbox>
> An 8 byte trigger is a safer option that causes better operation on weird
> hardware without signifcantly changing anything on good hardware. I really
> wish sio.c would be changed to set the trigger to 8 bytes by default, or at
> least have a flags option to change the trigger level.
> </soapbox>
>
> Jim
<hint> Couldn't something like this be turned into a tuneable nob
via sysctl? </hint> Software settable UART buffering is available on MS
OSes, could we not mimic this in someway?
-Kevin
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