Messages in this thread | | | Date | Wed, 16 Aug 2006 16:42:22 +0200 | From | Erik Mouw <> | Subject | Re: How to avoid serial port buffer overruns? |
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On Wed, Aug 16, 2006 at 08:35:05AM -0600, Robert Hancock wrote: > Raphael Hertzog wrote: > >(Please CC me when replying) > > > >Hello, > > > >While using Linux on low-end (semi-embedded) hardware (386 SX 40Mhz, 8Mb > >RAM), I discovered that Linux on that machine would suffer from serial > >port buffer overruns quite easily if I use a baudrate high enough (I start > >loosing bytes at >19200 bauds and I would like to make it reliable up to > >115 kbauds). I check if overruns are happening with > >/proc/tty/driver/serial ("oe" field). > > What kind of serial port are you using? If it's an unbuffered 8250-type > port, it will NEVER be reliable at higher baud rates. You want a 16550 > (or better) port.
I've run a cable modem connection at 115k2 over a 16450 UART on a 386DX40 for years. The tricks were:
- hdparm -u 1 /dev/hda - play with IRQ priorities in such a way that the serial port UART was handled first (there used to be a kernel module to accomplish that in old debian releases)
Erik
-- +-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 -- | Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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