patch-2.3.99-pre7 linux/Documentation/IO-APIC.txt

• Lines: 118
• Date: Wed Dec 31 16:00:00 1969
• Orig file: v2.3.99-pre6/linux/Documentation/IO-APIC.txt
• Orig date: Sun Jul 25 10:26:01 1999

diff -u --recursive --new-file v2.3.99-pre6/linux/Documentation/IO-APIC.txt linux/Documentation/IO-APIC.txt
@@ -1,117 +0,0 @@
-Most (all) Intel-MP compliant SMP boards have the so-called 'IO-APIC',
-which is an enhanced interrupt controller, it enables us to route
-hardware interrupts to multiple CPUs, or to CPU groups.
-
-Linux supports all variants of compliant SMP boards, including ones with
-multiple IO-APICs. (multiple IO-APICs are used in high-end servers to
-distribute IRQ load further).
-
-There are (a few) known breakages in certain older boards, which bugs are
-usually worked around by the kernel. If your MP-compliant SMP board does
-not boot Linux, then consult the linux-smp mailing list archives first.
-
-If your box boots fine with enabled IO-APIC IRQs, then your
-/proc/interrupts will look like this one:
-
-   ---------------------------->
-  hell:~> cat /proc/interrupts
-             CPU0
-    0:    1360293    IO-APIC-edge  timer
-    1:          4    IO-APIC-edge  keyboard
-    2:          0          XT-PIC  cascade
-   13:          1          XT-PIC  fpu
-   14:       1448    IO-APIC-edge  ide0
-   16:      28232   IO-APIC-level  Intel EtherExpress Pro 10/100 Ethernet
-   17:      51304   IO-APIC-level  eth0
-  NMI:          0
-  ERR:          0
-  hell:~>
-  <----------------------------
-
-some interrupts are still listed as 'XT PIC', but this is not a problem,
-none of those IRQ sources is performance-critical.
-
-
-in the unlikely case that your board does not create a working mp-table,
-you can use the pirq= boot parameter to 'hand-construct' IRQ entries. This
-is nontrivial though and cannot be automated. One sample /etc/lilo.conf
-entry:
-
-	append="pirq=15,11,10"
-
-the actual numbers depend on your system, on your PCI cards and on their
-PCI slot position. Usually PCI slots are 'daisy chained' before they are
-connected to the PCI chipset IRQ routing facility (the incoming PIRQ1-4
-lines):
-
-               ,-.        ,-.        ,-.        ,-.        ,-.
-     PIRQ4 ----| |-.    ,-| |-.    ,-| |-.    ,-| |--------| |
-               |S|  \  /  |S|  \  /  |S|  \  /  |S|        |S|
-     PIRQ3 ----|l|-. `/---|l|-. `/---|l|-. `/---|l|--------|l|
-               |o|  \/    |o|  \/    |o|  \/    |o|        |o|
-     PIRQ2 ----|t|-./`----|t|-./`----|t|-./`----|t|--------|t|
-               |1| /\     |2| /\     |3| /\     |4|        |5|
-     PIRQ1 ----| |-  `----| |-  `----| |-  `----| |--------| |
-               `-'        `-'        `-'        `-'        `-'
-
-every PCI card emits a PCI IRQ, which can be INTA,INTB,INTC,INTD:
-
-                               ,-.
-                         INTD--| |
-                               |S|
-                         INTC--|l|
-                               |o|
-                         INTB--|t|
-                               |x|
-                         INTA--| |
-                               `-'
-
-These INTA-D PCI IRQs are always 'local to the card', their real meaning
-depends on which slot they are in. If you look at the daisy chaining diagram,
-a card in slot4, issuing INTA IRQ, it will end up as a signal on PIRQ2 of
-the PCI chipset. Most cards issue INTA, this creates optimal distribution
-between the PIRQ lines. (distributing IRQ sources properly is not a
-necessity, PCI IRQs can be shared at will, but it's a good for performance
-to have non shared interrupts). Slot5 should be used for videocards, they
-do not use interrupts normally, thus they are not daisy chained either.
-
-so if you have your SCSI card (IRQ11) in Slot1, Tulip card (IRQ9) in
-Slot2, then you'll have to specify this pirq= line:
-
-	append="pirq=11,9"
-
-the following script tries to figure out such a default pirq= line from
-your PCI configuration:
-
-	echo -n pirq=; echo `scanpci | grep T_L | cut -c56-` | sed 's/ /,/g'
-
-note that this script wont work if you have skipped a few slots or if your
-board does not do default daisy-chaining. (or the IO-APIC has the PIRQ pins
-connected in some strange way). E.g. if in the above case you have your SCSI
-card (IRQ11) in Slot3, and have Slot1 empty:
-
-	append="pirq=0,9,11"
-
-[value '0' is a generic 'placeholder', reserved for empty (or non-IRQ emitting)
-slots.]
-
-generally, it's always possible to find out the correct pirq= settings, just
-permute all IRQ numbers properly ... it will take some time though. An
-'incorrect' pirq line will cause the booting process to hang, or a device
-won't function properly (if it's inserted as eg. a module).
-
-If you have 2 PCI buses, then you can use up to 8 pirq values. Although such
-boards tend to have a good configuration.
-
-Be prepared that it might happen that you need some strange pirq line:
-
-	append="pirq=0,0,0,0,0,0,9,11"
-
-use smart try-and-err techniques to find out the correct pirq line ...
-
-good luck and mail to linux-smp@vger.rutgers.edu or
-linux-kernel@vger.rutgers.edu if you have any problems that are not covered
-by this document.
-
--- mingo
-