

Re: PnP modem woes continue, IRQ never fires for modem

On Tue, Dec 02, 1997 at 04:03:29PM -0600, Charles Read wrote:
>     [BTW, what is a 'Legacy device', and why would
>     you need it for a PnP modem?]

A legacy device is a non-PnP device. You need to tell your BIOS
about them because it can't detect what IRQs/DMA channels they are using,
and you don't want it to configure your PnP devices to conflict.

> a. For the /etc/isapnp.conf file below, how do you know
>    what ID to use for the DMA?  ie, I can see from Win95
>    that I need channels 7 and 6, but should I use 
>    (DMA 0 (Channel 7))  and  (DMA 1 (Channel 6))
>    or should I use
>    (DMA 0 (Channel 7))  and  (DMA 0 (Channel 6))
>   or something else?  Or does the DMA 0/1 ID not matter?

It probably doesn't matter, but try both. But I suspect
the sound cabling & DMA channels are just for voice modes
like SVD and aren't really affecting your ability
to talk to the modem at all.

> c. I noticed under the Device>Resources tab for my modem
>     in Win95 that two distinct ranges are given:  0x3f8 and
>     0x100.   I always use 0x3f8 (or 0x2f8).  What is the
>     purpose of the second range starting at 0x100?


> #             Number of IO addresses required: 8
> (IO 0 (BASE 0x03f8))
> #       Logical device decodes 16 bit IO address lines
> #             Minimum IO base address 0x0100
> #             Maximum IO base address 0x03f8
> #             IO base alignment 8 bytes
> #             Number of IO addresses required: 8
> # (IO 1 (BASE 0x0100))

If you enable this, Linux will use 0x100 as well for it;
I don't know why that is useful though. It appears in
all four possible configurations so it may be worth enabling.

You mentioned that it doesn't appear in
/proc/interrupts; what about /proc/ioports?


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