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IRQ and Number of Devices

 
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Old 06-27-2013
IRQ and Number of Devices
Hello everyone. I feel that I'm about to answer my own question, but I just want to be sure that I'm right. I know computers all use, at a very low level, the IRQ system of interrupting the CPU when it needs something. My questions are as follows:

1. Does the device in question, say.. a mouse, need to use the interrupt wire every single time, I use it? Say if the CPU is potentially idle, and I tap a few keys, even though the CPU wasn't busy, will it still use the interrupt feature? Or intteruppting the CPU only done when it has other things it's busy with?

2. How can there only be 16 IRQ devices? Also considering that 3 of them are already taken, (timer, keyboard, and clock) and that 2 & 9 are the same. Doesn't this mean that if I plug in 16 devices into a 20port usb hub that I'd be out of device room? Or does the usb bus count as 1 device? Same goes for SATA ports? I have 4 SATA ports on my motherboard. if I plug in 4 SATA hard drives, does that mean i'm filling up 4 seperate IRQ slots?


Thanks for the help in advance!
 
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LEARN ABOUT SUNOS

pcic

pcic(7D)																  pcic(7D)

NAME

       pcic - Intel i82365SL PC Card Interface Controller

       The  Intel i82365SL PC Card interface controller provides one or more PCMCIA PC card sockets. The pcic driver implements a PCMCIA bus nexus
       driver.

       The driver provides basic support for the Intel 82365SL and compatible chips. The chips that have been tested are:

	 o  Intel 82365SL

	 o  Cirrus Logic PD6710/PD6720/PD6722

	 o  Vadem VG365/VG465/VG468/VG469

	 o  Toshiba PCIC and ToPIC

	 o  Ricoh RF5C366

	 o  Texas Instruments PCI1130/PCI1131/PCI1031

       While most systems using one of the above chips will work, some systems will not be supported due to hardware designs options that may  not
       be  software  detectable. Note that systems with CardBus interfaces are only supported in the non-legacy mode. Systems that only initialize
       the bridge to legacy mode and do not configure the PCI memory will not be supported.

       Direct access to the PCMCIA hardware is not supported. All device access must be through the Card Services interface of the DDI.

PRECONFIGURE

	 o  Install your add-in PC Card adapter prior to the Solaris installation.

	 o  Some systems have their built-in PC Card adapter disabled by default. Enable it prior to Solaris installation.

	 o  Requirements for a system depend on the combination of devices to be used. A typical two-socket system needs  at  least  8	Kbytes	of
	    address space, 16 bytes of I/O space, and three free IRQs. Following are general guidelines:

       +--------------+------------------------------------------------+
       |Address space | At  least  8 Kbytes are required with 4 Kbytes |
       |	      | per socket in the 640K-1MB range  (not	neces- |
       |	      | sarily	contiguous);  if there are three sock- |
       |	      | ets, at least 12 Kbytes are needed.	       |
       +--------------+------------------------------------------------+
       |I/O space     | At least 8 and preferably 16 bytes per socket. |
       +--------------+------------------------------------------------+
       |IRQs	      | One per socket,  plus  an  IRQ	for  the  pcic |
       |	      | device driver itself.			       |
       +--------------+------------------------------------------------+

CONFIGURATION

       There is one driver configuration property defined in the pcic.conf file.

       interrupt-priorities=11;        This property must be defined and must not be modified from the default value.

   Initial Installation and Configuration
       To perform initial installation and configuration, do the following steps:

       1.  Consult the Configuration Assistant for address space, I/O space, and IRQs already used by system devices.

       2.  Insert the PC Card adapter.

       3.  Install the Solaris software.

       4.  Reboot the system.

   Adding PC Card Support to a Previously Installed System
       To add PC card support to a previously installed system, do the following:

       1.  Become root.

       2.  Do a reconfiguration reboot to reallocate resources:

	   # touch /reconfigure

	   # reboot

       3.  Insert the PC Card adapter and turn on the machine.

       4.  Boot the system so that the PC Card device driver begins running with the new resources allocated.

   Allocating IRQs
       To allocate the IRQs, do the following:

       1.  Boot with the Configuration Assistant so you can review the resource usage.

       2.  Select  View/Edit Devices from the Device Tasks menu, and review the list of devices to see how many IRQs are being used. (There are 16
	   IRQs, from 0-15. Several IRQs are already assigned. For example, IRQ 3 is reserved for the second serial  port,  COM2,  and	IRQ  7	is
	   reserved for the parallel port.)

       3.  If  your  system  has an unused COM2 or parallel port, delete the device to free the IRQ resource for a PC Card. To do this, select the
	   serial port device using IRQ 3 or the parallel port using IRQ 7, and choose Delete Device. Next,  choose  Continue  to  return  to  the
	   Device Tasks menu, then save the configuration.

       4.  Boot the Solaris software.

       /kernel/drv/pcic 	       pcic driver

       /kernel/drv/pcic.conf	       pcic configuration file

       pcmcia(7D), stp4020(7D)

								    20 Oct 2000 							  pcic(7D)