Date: Sun, 17 May 1998 20:01:22 GMT From: jak@cetlink.net (John Kelly) To: Jt <hometeam@techpower.net> Cc: questions@FreeBSD.ORG Subject: Re: sio driver Message-ID: <355f392d.92799981@mail.cetlink.net> In-Reply-To: <Pine.BSF.3.96.980517103543.1143B-100000@techpower.net> References: <Pine.BSF.3.96.980517103543.1143B-100000@techpower.net>
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On Sun, 17 May 1998 10:38:09 -0400 (EDT), Jt <hometeam@techpower.net> wrote: >Yes could I see your kernel config file on how you change the fifo buffer? Here it is: > options "COM_MULTIPORT" > device sio0 at isa? port 0x100 tty flags 0x18000085 irq 9 vector siointr > device sio1 at isa? port 0x108 tty flags 0x18000085 > device sio2 at isa? port 0x110 tty flags 0x18000085 > device sio3 at isa? port 0x118 tty flags 0x18000085 > ^^ Notice the (hex) 18 above. It says use a transmit FIFO size of 24 bytes. Be sure to specify a size less than or equal the actual UART transmit FIFO size. I chose 24 because I had planned on poking the EFR to set the transmit FIFO trigger level to 8, and in that case I would always be safe in loading 24 (8 + 24 = 32 maximum size) bytes into the UART. I've not done that yet, so my 650 UART still runs in 550 compatibility mode where the transmit interrupt occurs when the transmit FIFO goes empty (rather than with 8 bytes remaining to transmit). The motive for using a transmit trigger level greater that zero is avoidance of transmit underruns, but I don't really know if it will make a measurable performance difference with SIO or not. So if you run your 650 UART in 550 compatibility mode, you could use the full 32 bytes transmit FIFO instead of only 24 as I have done. >I am running stable I wonder if this option is available in the 2.2.6 >release? I don't think so. But you can download the -current 980515 SNAP from current.FreeBSD.org. It seems about as "stable" as they ever get. Takes about 6 - 8 hours on a 28.8 modem, plus a few more hours for X if you want that too. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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