Lost characters on serial console

Hello,

we loose characters on the serial consol during receiving at 115kbaud. Especially if the ide harddisk is used during reception.

We use a 300MHz Goede MediaGX, with a 16550A serial port (16 byte FIFO). We tuned the Harddisk with hdparm, which reduced the problem, but it still exists.

We tried several Kernels: 2.4.4, 2.4.20, 2.4.24 and 2.6.0 and several patches "preempt" and "low-lattency". No changes at all.
We used ext2 and ReiserFS file system.

There were some messages on this problem in the mailing list, but they are years old and we did not find real hints, how to solve.

Can anybody help, can we help with debugging, testing?

Thanks a lot
Detlef Schmicker