serial performance

Trifle Menot
2010-03-12T15:57:44Z

If I start dosemu -s with this:

> $_ports = "fast range 0x3F8,0x3FF"
> $_irqpassing = "4"

A speed of 57600 looks fast, like it should be. But if I omit the
direct hardware access, and try this:

> $_com1 = "/dev/ttyS0 irq 4"

57600 still works, but looks much slower on the remote side of a null
modem cable. Seems like I read where the code traps serial port writes
and buffers data to /dev/ttyS0. Is the trapping causing the slowdown?
Is there a cure?

I don't want to use direct hardware access. I tested it that way, only
to see how things work.

I'm using the latest dosemu svn code. I first tried a 2.6.32 kernel on
arch linux, but got a kernel panic, then tried a suse 2.6.11 kernel, and
got these results. Both were i386 only, never x86_64.