ufdti issues - compile kernel without module
Bram Van Steenlandt
bram at diomedia.be
Sun Sep 14 19:57:56 UTC 2014
I'm porting a plc/automation system from linux to freebsd and while
doing so I've discovered some issues with uftdi (the system use a couple
of rs485 connections).
Under linux I'v used the ftdi adapters as com ports, they show up as
/dev/ttyUSB0 etc, this works mostly ok.
With freebsd, I've found that while ufdti works it's much slower than
it's linux counterpart,
with linux the Tx/Rx leds are flashing rapidly, I can poll a plc 10
times per second, with freebsd this was about 2 times per second, serial
parameters are the same.
I've found other reports online from people who experience similar issues.
I then tried porting the application so that it uses libftdi (in serial
mode), when using libftdi performance was very good also on freebsd.
So the problem must be the uftdi kernel module (I think).
You can't use libftdi if you have the uftdi kernel module loaded.
I did not succeed in building a kernel without the uftdi module,
deleting it from /boot/kernel works but probably isn't "the way".
but this makes no difference, when running make buildkernel it still
build the module.
Is there a way to do this ?
Or does freebsd have it's own blacklist system ?
I've found various information online and I've tried various things but
I can't seem to get this to work.
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