Date: Fri, 15 Sep 2000 22:38:19 -0600 From: Allen Campbell <allenc@verinet.com> To: Joseph Jacobson <jacobson@pobox.com> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: silo overflow Message-ID: <39C2F93B.7275FD7B@verinet.com> References: <200009160007.e8G078n02639@home.my.domain>
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Joseph Jacobson wrote:
>
> Just got this error, doing a 'make fetch' over ppp, while running mpg123.
> Kernel config can be provided if needed.
>
> sio0: 1 more silo overflow (total 1)
> sio0: 1 more silo overflow (total 2)
> sio0: 1 more silo overflow (total 3)
> sio0: 1 more silo overflow (total 4)
> sio0: 1 more silo overflow (total 5)
> sio0: 1 more silo overflow (total 6)
This is a frequently reported problem. It is, for the most part,
harmless. You will find an abundance of history by searching the mail
archives. Apparently some recent changes involving 'fast' interrupt
handling will cause FreeBSD to neglect a serial port for a bit too long,
and incoming data isn't read from the device before it is lost.
The following patch seems to help. It lowers the fifo threshold a bit
causing more frequent reads from the device. It also increases
interrupt frequency which, to some, seems rather tragic. I've never
felt any pain as a result of 'too many' interrupts from a serial port,
but I like not getting the silo overflows. This hack isn't Right(tm),
but it does work.
--- sio.c.orig Wed Aug 16 09:29:34 2000
+++ sio.c Fri Sep 1 14:53:47 2000
@@ -2345,7 +2345,7 @@
* latencies are larger.
*/
com->fifo_image = t->c_ospeed <= 4800
- ? FIFO_ENABLE : FIFO_ENABLE |
FIFO_RX_HIGH;
+ ? FIFO_ENABLE : FIFO_ENABLE |
FIFO_RX_MEDH;
#ifdef COM_ESP
/*
* The Hayes ESP card needs the fifo DMA mode bit set
No promises about whether this patch will apply to your version of
src/sys/isa/sio.c. I usually just change the one line by hand.
--
Allen Campbell | Lurking at the bottom of the
allenc@verinet.com | gravity well, getting old.
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