Date: Fri, 12 Sep 1997 21:03:55 +0000 From: Invis <invis@visi.com> To: freebsd-questions@freebsd.org Subject: Re: refined silo overflow question Message-ID: <19970912210355.16266@visi.com> In-Reply-To: <199709121416.KAA00211@myplace.org>; from Keith Leonard on Fri, Sep 12, 1997 at 10:16:30AM -0400 References: <199709121416.KAA00211@myplace.org>
next in thread | previous in thread | raw e-mail | index | archive | help
> >system /kernel: sio1: 1 more silo overflow (total of 10) for example. > > ************* THE IMPORTANT PART *************************** > > The 16550 fifo trigger level is set very agressively (to 14) to maximise > efficiency. Dynamic adjustment of the trigger level (to 8, then 4, then > 2, then 1) after silo overflows is #ifdef'ed off. A level of 8 would > probably work for all 386/16 and faster systems with only 4 ports, > provided they don't have bus-hogging DMA controller. You currently have > to edit the sources to change the level. > > ************************************************************ > > Can someone tell me where this 'trigger level' is set and > how to change it so that I might get rid of an annoying > message to console. I need to recompile the kernel for the > laptop anyway and it would sure be nice to clean up a few > loose ends. (using ver. 2.1.5) > I just took a quick look at the kernel source, it looks to be in the file sio.c in the sys/i386/isa directory. I *think* the FIFO size is set in line 866 of the code, but the variable it sets is com->tx_fifo_size is set to 16.. maybe this is just a mask? If you want to mod the kernel, that's up to you, however I would strongly suggest taking a look at the code for yourself if you want to, and not taking what I said for granted :) But you bring up an interesting topic in this message -- Should there be some place (or is there a place) where users can set comm port parameters such as the FIFO level, etc in the UART? invis, invis@visi.com
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19970912210355.16266>