Messages in this thread | | | Date | Sun, 6 Jun 1999 00:23:19 +0100 (GMT) | From | Riley Williams <> | Subject | Re: Hard coding default COM3/4 IRQ. |
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Hi Mike.
>>> There is a CONFIG option for doing autodetection of the IRQ, >>> CONFIG_SERIAL_SHARE_IRQ; you need to answer yes to >>> CONFIG_SERIAL_EXTENDED to see the extra serial config options. >>> The problem is that it doesn't always work.
>>> I suspect that Linux folk very often have a lot more random >>> hardware attached to their machines than Windows folks, and >>> these random ISA bus cards can confuse an autodetection >>> algorithm.
>> Does this also mean that auto IRQ detection using setserial is >> not reliable?
>> BTW: what sort of confusion do you mean?
> Yes. When I do auto IRQ with setserial, it returns something > like: IRQ -1023128419585
> Since I only have 15 IRQ's on my machine, and since some of them > are taken, and none negative - I'd say that setserial > autodetection doesn't work right. My modem is on IRQ, which > nothing else is conflicting with. Windows 95 gets the IRQ right > without asking, it is not a winmodem.
> I haven't tried the kernel level autoirq yet... I will though > soon...
I checked out the kernel autoirq for COM3 and COM4 on standard IO addresses a while back, when 2.0.35 was current, and even on systems where the hardware was set to irq's that conflicted with other hardware in the system, it ALWAYS got the IRQ correct, and NEVER locked one of those systems up.
Because of this, I proposed a patch that enabled the autoirq feature for these two ports. It was rejected by the maintainer, Ted Ts'o, on the grounds that enabling autoirq for HUB6 and the AST FourPort cards (neither of which were affected by my patch) could result in the kernel locking the system up.
I tried to point out to Ted that my patch did not touch support for any of the cards he claimed to be worried about, but found Ted less than interested in that fact. As a result, I will be rather surprised to hear that any such patch has been accepted, unless it was submitted by Linus himself.
Since the serial probing is done differently in the 2.2.x kernels, I'm not planning on resubmitting my patch, and I'm also not planning on wasting my time developing an equivalent patch for the 2.2.x kernels.
Best wishes from Riley.
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