FAQ (Frequently Asked Question) # 163202.faq
How to use non-standard IRQs
DOCUMENT ID: 1632-02
SYNOPSIS: How to use non-standard IRQs
OS RELEASE: Solaris 2.4 x86
KEYWORDS: irq asy com x86
SYMPTOMS:
You want to add a new COM port or other device, but don't want the
problems associated with sharing an IRQ.
DESCRIPTION:
You have additional COM ports and want to use a non-standard IRQ setting
so it doesn't share an IRQ with another COM port or any other device.
This is often very important for machine which also run DOS/Windows,
which doesn't share IRQs very well.
SOLUTION:
This can be done by editting the configuration file for the driver used
by the device you are adding. In the case of a COM port the is the asy
driver and the configuration file will be /kernel/drv/asy.conf.
Here is a sample line for a typical COM3 configuration:
name="asy" class="sysbus" interrupts=12,4 reg=0x3E8,0,0 ioaddr=0x3E8;
The "interrupts=12,4" is the part that says what IRQ is being used by a
device. The first number is a priority level value for the driver and
should not be changed under normal circumstances. The second number is
the hardware IRQ number that matches the IRQ number you would refer to
in MS-DOS.
The problem with this configuration is that COM1, which often is where
you have a mouse, is also using IRQ 4. Many modem and add-in serial
port cards give you many possible IRQ settings for the card. Common
ones are 2 or 9 (they are the same), 5, or 10-12. Some cards will offer
others but these are the ones that are typically unused by other cards.
First verify that you know the IRQs being used by every board in your
system. This can be a little more difficult with PCI cards, because
their IRQs are assigned by the BIOS. We have a small program you can
download that will display the IRQs (along with a lot more info) for
your PCI devices. It is called PRTPCI.EXE and must be run under DOS.
After you have found a free IRQ, or decided you can change the IRQ of
another device to free up one you can use for the device you are adding,
you can do a "touch /reconfigure" followed by an "init 6" to reboot the
system. After the system has shutdown and you see the BIOS messages
start coming up you can turn the machine off. You can now insert your
new card and change any existing cards in the system.
You can now boot up the system and it should reconfigure itself. Watch
the messages to make sure no errors occur.
If you forgot to do the "touch /reconfigure" before rebooting, never
fear. You can also do the "b -r" command when it asks if you want to do
a Jumpstart boot. The does the same thing as a "touch /reconfigure".
To verify that your new device was recognized do a "prtconf" command and
you should see it listed there. In the case of adding a COM3 device you
will see an "asy, instance #2" appear. The COM devices for 1 to 4 are
numbered as instances 0 to 3 by Solaris using the standard I/O port
addresses to distinguish them as instances 0 to 3.
DATE APPROVED: 12/25/95
Questions or comments?