€•ÍA      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ)/translations/zh_CN/arch/x86/i386/IO-APIC”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/zh_TW/arch/x86/i386/IO-APIC”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/it_IT/arch/x86/i386/IO-APIC”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/ja_JP/arch/x86/i386/IO-APIC”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/ko_KR/arch/x86/i386/IO-APIC”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒPortuguese (Brazilian)”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/pt_BR/arch/x86/i386/IO-APIC”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh–sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/sp_SP/arch/x86/i386/IO-APIC”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ SPDX-License-Identifier: GPL-2.0”h]”hŒ SPDX-License-Identifier: GPL-2.0”…””}”hh·sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1hµhhh²hh³ŒC/var/lib/git/docbuild/linux/Documentation/arch/x86/i386/IO-APIC.rst”h´KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒIO-APIC”h]”hŒIO-APIC”…””}”(hhÏh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÍhhÊh²hh³hÇh´KubhŒ
field_list”“”)”}”(hhh]”hŒfield”“”)”}”(hhh]”(hŒ
field_name”“”)”}”(hŒAuthor”h]”hŒAuthor”…””}”(hhéh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hçhhäh³hÇh´K ubhŒ
field_body”“”)”}”(hŒIngo Molnar <mingo@kernel.org>
”h]”hŒ	paragraph”“”)”}”(hŒIngo Molnar <mingo@kernel.org>”h]”(hŒIngo Molnar <”…””}”(hhÿh²hh³Nh´NubhŒ	reference”“”)”}”(hŒmingo@kernel.org”h]”hŒmingo@kernel.org”…””}”(hj	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œmailto:mingo@kernel.org”uh1j  hhÿubhŒ>”…””}”(hhÿh²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´Khhùubah}”(h]”h ]”h"]”h$]”h&]”uh1h÷hhäubeh}”(h]”h ]”h"]”h$]”h&]”uh1hâh³hÇh´Khhßh²hubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝhhÊh²hh³hÇh´Kubhþ)”}”(hXA  Most (all) Intel-MP compliant SMP boards have the so-called 'IO-APIC',
which is an enhanced interrupt controller. It enables us to route
hardware interrupts to multiple CPUs, or to CPU groups. Without an
IO-APIC, interrupts from hardware will be delivered only to the
CPU which boots the operating system (usually CPU#0).”h]”hXE  Most (all) Intel-MP compliant SMP boards have the so-called â€˜IO-APICâ€™,
which is an enhanced interrupt controller. It enables us to route
hardware interrupts to multiple CPUs, or to CPU groups. Without an
IO-APIC, interrupts from hardware will be delivered only to the
CPU which boots the operating system (usually CPU#0).”…””}”(hj5  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´K	hhÊh²hubhþ)”}”(hŒªLinux 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.”h]”hŒªLinux 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.”…””}”(hjC  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KhhÊh²hubhþ)”}”(hŒÙThere are (a few) known breakages in certain older boards, such bugs are
usually worked around by the kernel. If your MP-compliant SMP board does
not boot Linux, then consult the linux-smp mailing list archives first.”h]”hŒÙThere are (a few) known breakages in certain older boards, such bugs are
usually worked around by the kernel. If your MP-compliant SMP board does
not boot Linux, then consult the linux-smp mailing list archives first.”…””}”(hjQ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KhhÊh²hubhþ)”}”(hŒfIf your box boots fine with enabled IO-APIC IRQs, then your
/proc/interrupts will look like this one::”h]”hŒeIf your box boots fine with enabled IO-APIC IRQs, then your
/proc/interrupts will look like this one:”…””}”(hj_  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KhhÊh²hubhŒliteral_block”“”)”}”(hX‡  hell:~> cat /proc/interrupts
           CPU0
  0:    1360293    IO-APIC-edge  timer
  1:          4    IO-APIC-edge  keyboard
  2:          0          XT-PIC  cascade
 13:          1          XT-PIC  fpu
 14:       1448    IO-APIC-edge  ide0
 16:      28232   IO-APIC-level  Intel EtherExpress Pro 10/100 Ethernet
 17:      51304   IO-APIC-level  eth0
NMI:          0
ERR:          0
hell:~>”h]”hX‡  hell:~> cat /proc/interrupts
           CPU0
  0:    1360293    IO-APIC-edge  timer
  1:          4    IO-APIC-edge  keyboard
  2:          0          XT-PIC  cascade
 13:          1          XT-PIC  fpu
 14:       1448    IO-APIC-edge  ide0
 16:      28232   IO-APIC-level  Intel EtherExpress Pro 10/100 Ethernet
 17:      51304   IO-APIC-level  eth0
NMI:          0
ERR:          0
hell:~>”…””}”hjo  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´KhhÊh²hubhþ)”}”(hŒ{Some interrupts are still listed as 'XT PIC', but this is not a problem;
none of those IRQ sources is performance-critical.”h]”hŒSome interrupts are still listed as â€˜XT PICâ€™, but this is not a problem;
none of those IRQ sources is performance-critical.”…””}”(hj}  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´K'hhÊh²hubhþ)”}”(hŒäIn the unlikely case that your board does not create a working mp-table,
you can use the pirq= boot parameter to 'hand-construct' IRQ entries. This
is non-trivial though and cannot be automated. One sample /etc/lilo.conf
entry::”h]”hŒçIn the unlikely case that your board does not create a working mp-table,
you can use the pirq= boot parameter to â€˜hand-constructâ€™ IRQ entries. This
is non-trivial though and cannot be automated. One sample /etc/lilo.conf
entry:”…””}”(hj‹  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´K+hhÊh²hubjn  )”}”(hŒappend="pirq=15,11,10"”h]”hŒappend="pirq=15,11,10"”…””}”hj™  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´K0hhÊh²hubhþ)”}”(hŒâThe actual numbers depend on your system, on your PCI cards and on their
PCI slot position. Usually PCI slots are 'daisy chained' before they are
connected to the PCI chipset IRQ routing facility (the incoming PIRQ1-4
lines)::”h]”hŒåThe actual numbers depend on your system, on your PCI cards and on their
PCI slot position. Usually PCI slots are â€˜daisy chainedâ€™ before they are
connected to the PCI chipset IRQ routing facility (the incoming PIRQ1-4
lines):”…””}”(hj§  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´K2hhÊh²hubjn  )”}”(hX	            ,-.        ,-.        ,-.        ,-.        ,-.
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 ----| |-  `----| |-  `----| |-  `----| |--------| |
          `-'        `-'        `-'        `-'        `-'”h]”hX	            ,-.        ,-.        ,-.        ,-.        ,-.
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 ----| |-  `----| |-  `----| |-  `----| |--------| |
          `-'        `-'        `-'        `-'        `-'”…””}”hjµ  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´K7hhÊh²hubhþ)”}”(hŒGEvery PCI card emits a PCI IRQ, which can be INTA, INTB, INTC or INTD::”h]”hŒFEvery PCI card emits a PCI IRQ, which can be INTA, INTB, INTC or INTD:”…””}”(hjÃ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KAhhÊh²hubjn  )”}”(hŒY      ,-.
INTD--| |
      |S|
INTC--|l|
      |o|
INTB--|t|
      |x|
INTA--| |
      `-'”h]”hŒY      ,-.
INTD--| |
      |S|
INTC--|l|
      |o|
INTB--|t|
      |x|
INTA--| |
      `-'”…””}”hjÑ  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´KChhÊh²hubhþ)”}”(hXK  These INTA-D PCI IRQs are always 'local to the card', their real meaning
depends on which slot they are in. If you look at the daisy chaining diagram,
a card in slot4, issuing INTA IRQ, it will end up as a signal on PIRQ4 of
the PCI chipset. Most cards issue INTA, this creates optimal distribution
between the PIRQ lines. (distributing IRQ sources properly is not a
necessity, PCI IRQs can be shared at will, but it's a good for performance
to have non shared interrupts). Slot5 should be used for videocards, they
do not use interrupts normally, thus they are not daisy chained either.”h]”hXQ  These INTA-D PCI IRQs are always â€˜local to the cardâ€™, their real meaning
depends on which slot they are in. If you look at the daisy chaining diagram,
a card in slot4, issuing INTA IRQ, it will end up as a signal on PIRQ4 of
the PCI chipset. Most cards issue INTA, this creates optimal distribution
between the PIRQ lines. (distributing IRQ sources properly is not a
necessity, PCI IRQs can be shared at will, but itâ€™s a good for performance
to have non shared interrupts). Slot5 should be used for videocards, they
do not use interrupts normally, thus they are not daisy chained either.”…””}”(hjß  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KMhhÊh²hubhþ)”}”(hŒyso if you have your SCSI card (IRQ11) in Slot1, Tulip card (IRQ9) in
Slot2, then you'll have to specify this pirq= line::”h]”hŒzso if you have your SCSI card (IRQ11) in Slot1, Tulip card (IRQ9) in
Slot2, then youâ€™ll have to specify this pirq= line:”…””}”(hjí  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KVhhÊh²hubjn  )”}”(hŒappend="pirq=11,9"”h]”hŒappend="pirq=11,9"”…””}”hjû  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´KYhhÊh²hubhþ)”}”(hŒ`the following script tries to figure out such a default pirq= line from
your PCI configuration::”h]”hŒ_the following script tries to figure out such a default pirq= line from
your PCI configuration:”…””}”(hj	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´K[hhÊh²hubjn  )”}”(hŒDecho -n pirq=; echo `scanpci | grep T_L | cut -c56-` | sed 's/ /,/g'”h]”hŒDecho -n pirq=; echo `scanpci | grep T_L | cut -c56-` | sed 's/ /,/g'”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´K^hhÊh²hubhþ)”}”(hX  note that this script won't 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::”h]”hX  note that this script wonâ€™t 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:”…””}”(hj%  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´K`hhÊh²hubjn  )”}”(hŒappend="pirq=0,9,11"”h]”hŒappend="pirq=0,9,11"”…””}”hj3  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´KehhÊh²hubhþ)”}”(hŒW[value '0' is a generic 'placeholder', reserved for empty (or non-IRQ emitting)
slots.]”h]”hŒ_[value â€˜0â€™ is a generic â€˜placeholderâ€™, reserved for empty (or non-IRQ emitting)
slots.]”…””}”(hjA  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KghhÊh²hubhþ)”}”(hX  Generally, it's always possible to find out the correct pirq= settings, just
permute all IRQ numbers properly ... it will take some time though. An
'incorrect' pirq line will cause the booting process to hang, or a device
won't function properly (e.g. if it's inserted as a module).”h]”hX$  Generally, itâ€™s always possible to find out the correct pirq= settings, just
permute all IRQ numbers properly ... it will take some time though. An
â€˜incorrectâ€™ pirq line will cause the booting process to hang, or a device
wonâ€™t function properly (e.g. if itâ€™s inserted as a module).”…””}”(hjO  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KjhhÊh²hubhþ)”}”(hŒvIf you have 2 PCI buses, then you can use up to 8 pirq values, although such
boards tend to have a good configuration.”h]”hŒvIf you have 2 PCI buses, then you can use up to 8 pirq values, although such
boards tend to have a good configuration.”…””}”(hj]  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KohhÊh²hubhþ)”}”(hŒGBe prepared that it might happen that you need some strange pirq line::”h]”hŒFBe prepared that it might happen that you need some strange pirq line:”…””}”(hjk  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KrhhÊh²hubjn  )”}”(hŒappend="pirq=0,0,0,0,0,0,9,11"”h]”hŒappend="pirq=0,0,0,0,0,0,9,11"”…””}”hjy  sbah}”(h]”h ]”h"]”h$]”h&]”hÅhÆuh1jm  h³hÇh´KthhÊh²hubhþ)”}”(hŒJUse smart trial-and-error techniques to find out the correct pirq line ...”h]”hŒJUse smart trial-and-error techniques to find out the correct pirq line ...”…””}”(hj‡  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KvhhÊh²hubhþ)”}”(hŒGood luck and mail to linux-smp@vger.kernel.org or
linux-kernel@vger.kernel.org if you have any problems that are not covered
by this document.”h]”(hŒGood luck and mail to ”…””}”(hj•  h²hh³Nh´Nubj  )”}”(hŒlinux-smp@vger.kernel.org”h]”hŒlinux-smp@vger.kernel.org”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œ mailto:linux-smp@vger.kernel.org”uh1j  hj•  ubhŒ or
”…””}”(hj•  h²hh³Nh´Nubj  )”}”(hŒlinux-kernel@vger.kernel.org”h]”hŒlinux-kernel@vger.kernel.org”…””}”(hj±  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œ#mailto:linux-kernel@vger.kernel.org”uh1j  hj•  ubhŒ@ if you have any problems that are not covered
by this document.”…””}”(hj•  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hýh³hÇh´KxhhÊh²hubeh}”(h]”Œio-apic”ah ]”h"]”Œio-apic”ah$]”h&]”uh1hÈhhh²hh³hÇh´Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”hÇuh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(hÍNŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
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