Dropped character question

• Messages sorted by:[ date ][ thread ][ subject ][ author ]

On Wed, 4 Aug 1999, Gert Doering wrote:

> I tend to disagree on this - as the RTS flow control has to be done by the
> kernel drivers, it will only be activated if the kernel RX buffers fill
> (and not if the 16550A's buffers are full).  If the kernel buffers fill,

You are right. Only on special hardware (such as the Hayes ESP ISA
card I am using) the RTS flow control is handled by the serial port.

I quickly looked in linux's serial driver, and the upper level tty
routines control RTS (ie when either serial buffer or application
buffer, I didn't look).

It *is* possible that if there are so many interrupts the system just
can process them and nothing else, the serial buffer fills, and RTS
drops.

Another case is obviously this one:

> it means your (our) application hasn't been fast enough to read an 38400
> bps data stream - meager 4 Kbyte/sec. - from the tty device, and this
> hints at *REAL* problems in the system or the application.