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Tomcat III I have 2 mb serial ports, as well as two AST 4-port cards. These often monitor router console screens; i.e. VT100 emulation w/miniterm. All the ports have, over time, dropped a bit|byte here & there, as seen by scrambled screen displays. A ^L-stype screen repaint clears same. But with 6.1, the problem is visibly worse -- now, in only 15 minutes or so, the display is a real mess. This seems true more on the 4-ports than the 2 integral ports, but still ttyS0|1 are worse than in the past. I checked with Ted Tso & he had no immediate answers.
This is a kernel driver problem ...
Does hdparm -u1 /dev/hda fix this [See man hdparm first]
Fog lifts slightly. Looks like 6.1 upgrade (now 2.2.12-20) put IDE drives in PIO mode. That likely explains why it got so much worse at that time. But note the problem exist[s,ed] (to a far lesser extent) even without being dumped in PIO. Would think 16550A's & 950's had enough buffer.
Im suprised you see it with -u1. What other drivers are on your box.
Ancient release, no reply