€•æ@Œsphinx.addnodes”Œdocument”“”)”}”(Œ rawsource”Œ”Œchildren”]”(Œ translations”Œ LanguagesNode”“”)”}”(hhh]”(hŒ pending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ refdomain”Œstd”Œreftype”Œdoc”Œ reftarget”Œ)/translations/zh_CN/arch/x86/i386/IO-APIC”Œmodname”NŒ classname”NŒ refexplicit”ˆuŒtagname”hhh ubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ)/translations/zh_TW/arch/x86/i386/IO-APIC”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ)/translations/it_IT/arch/x86/i386/IO-APIC”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ)/translations/ja_JP/arch/x86/i386/IO-APIC”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ)/translations/ko_KR/arch/x86/i386/IO-APIC”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ)/translations/sp_SP/arch/x86/i386/IO-APIC”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h hhŒ _document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ SPDX-License-Identifier: GPL-2.0”h]”hŒ SPDX-License-Identifier: GPL-2.0”…””}”hh£sbah}”(h]”h ]”h"]”h$]”h&]”Œ xml:space”Œpreserve”uh1h¡hhhžhhŸŒC/var/lib/git/docbuild/linux/Documentation/arch/x86/i386/IO-APIC.rst”h KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒIO-APIC”h]”hŒIO-APIC”…””}”(hh»hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh¶hžhhŸh³h KubhŒ field_list”“”)”}”(hhh]”hŒfield”“”)”}”(hhh]”(hŒ field_name”“”)”}”(hŒAuthor”h]”hŒAuthor”…””}”(hhÕhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÓhhÐhŸh³h KubhŒ field_body”“”)”}”(hŒIngo Molnar ”h]”hŒ paragraph”“”)”}”(hŒIngo Molnar ”h]”(hŒ Ingo Molnar <”…””}”(hhëhžhhŸNh NubhŒ reference”“”)”}”(hŒmingo@kernel.org”h]”hŒmingo@kernel.org”…””}”(hhõhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œmailto:mingo@kernel.org”uh1hóhhëubhŒ>”…””}”(hhëhžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Khhåubah}”(h]”h ]”h"]”h$]”h&]”uh1hãhhÐubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÎhŸh³h KhhËhžhubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhh¶hžhhŸh³h Kubhê)”}”(hXAMost (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]”hXEMost (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).”…””}”(hj!hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h K hh¶hžhubhê)”}”(hŒªLinux supports all variants of compliant SMP boards, including ones with multiple IO-APICs. Multiple IO-APICs are used in high-end servers to distribute IRQ load further.”h]”hŒªLinux supports all variants of compliant SMP boards, including ones with multiple IO-APICs. Multiple IO-APICs are used in high-end servers to distribute IRQ load further.”…””}”(hj/hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Khh¶hžhubhê)”}”(hŒÙThere 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]”hŒÙThere 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.”…””}”(hj=hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Khh¶hžhubhê)”}”(hŒfIf your box boots fine with enabled IO-APIC IRQs, then your /proc/interrupts will look like this one::”h]”hŒeIf your box boots fine with enabled IO-APIC IRQs, then your /proc/interrupts will look like this one:”…””}”(hjKhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Khh¶hžhubhŒ literal_block”“”)”}”(hX‡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]”hX‡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:~>”…””}”hj[sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h Khh¶hžhubhê)”}”(hŒ{Some interrupts are still listed as 'XT PIC', but this is not a problem; none of those IRQ sources is performance-critical.”h]”hŒSome interrupts are still listed as ‘XT PIC’, but this is not a problem; none of those IRQ sources is performance-critical.”…””}”(hjihžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h K'hh¶hžhubhê)”}”(hŒäIn 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]”hŒçIn 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:”…””}”(hjwhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h K+hh¶hžhubjZ)”}”(hŒappend="pirq=15,11,10"”h]”hŒappend="pirq=15,11,10"”…””}”hj…sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h K0hh¶hžhubhê)”}”(hŒâThe 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]”hŒåThe 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):”…””}”(hj“hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h K2hh¶hžhubjZ)”}”(hX  ,-. ,-. ,-. ,-. ,-. PIRQ4 ----| |-. ,-| |-. ,-| |-. ,-| |--------| | |S| \ / |S| \ / |S| \ / |S| |S| PIRQ3 ----|l|-. `/---|l|-. `/---|l|-. `/---|l|--------|l| |o| \/ |o| \/ |o| \/ |o| |o| PIRQ2 ----|t|-./`----|t|-./`----|t|-./`----|t|--------|t| |1| /\ |2| /\ |3| /\ |4| |5| PIRQ1 ----| |- `----| |- `----| |- `----| |--------| | `-' `-' `-' `-' `-'”h]”hX  ,-. ,-. ,-. ,-. ,-. PIRQ4 ----| |-. ,-| |-. ,-| |-. ,-| |--------| | |S| \ / |S| \ / |S| \ / |S| |S| PIRQ3 ----|l|-. `/---|l|-. `/---|l|-. `/---|l|--------|l| |o| \/ |o| \/ |o| \/ |o| |o| PIRQ2 ----|t|-./`----|t|-./`----|t|-./`----|t|--------|t| |1| /\ |2| /\ |3| /\ |4| |5| PIRQ1 ----| |- `----| |- `----| |- `----| |--------| | `-' `-' `-' `-' `-'”…””}”hj¡sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h K7hh¶hžhubhê)”}”(hŒGEvery PCI card emits a PCI IRQ, which can be INTA, INTB, INTC or INTD::”h]”hŒFEvery PCI card emits a PCI IRQ, which can be INTA, INTB, INTC or INTD:”…””}”(hj¯hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h KAhh¶hžhubjZ)”}”(hŒY ,-. INTD--| | |S| INTC--|l| |o| INTB--|t| |x| INTA--| | `-'”h]”hŒY ,-. INTD--| | |S| INTC--|l| |o| INTB--|t| |x| INTA--| | `-'”…””}”hj½sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h KChh¶hžhubhê)”}”(hXKThese 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]”hXQThese 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.”…””}”(hjËhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h KMhh¶hžhubhê)”}”(hŒyso if you have your SCSI card (IRQ11) in Slot1, Tulip card (IRQ9) in Slot2, then you'll have to specify this pirq= line::”h]”hŒzso if you have your SCSI card (IRQ11) in Slot1, Tulip card (IRQ9) in Slot2, then you’ll have to specify this pirq= line:”…””}”(hjÙhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h KVhh¶hžhubjZ)”}”(hŒappend="pirq=11,9"”h]”hŒappend="pirq=11,9"”…””}”hjçsbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h KYhh¶hžhubhê)”}”(hŒ`the following script tries to figure out such a default pirq= line from your PCI configuration::”h]”hŒ_the following script tries to figure out such a default pirq= line from your PCI configuration:”…””}”(hjõhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h K[hh¶hžhubjZ)”}”(hŒDecho -n pirq=; echo `scanpci | grep T_L | cut -c56-` | sed 's/ /,/g'”h]”hŒDecho -n pirq=; echo `scanpci | grep T_L | cut -c56-` | sed 's/ /,/g'”…””}”hjsbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h K^hh¶hžhubhê)”}”(hXnote that this script won't work if you have skipped a few slots or if your board does not do default daisy-chaining. (or the IO-APIC has the PIRQ pins connected in some strange way). E.g. if in the above case you have your SCSI card (IRQ11) in Slot3, and have Slot1 empty::”h]”hXnote that this script won’t work if you have skipped a few slots or if your board does not do default daisy-chaining. (or the IO-APIC has the PIRQ pins connected in some strange way). E.g. if in the above case you have your SCSI card (IRQ11) in Slot3, and have Slot1 empty:”…””}”(hjhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h K`hh¶hžhubjZ)”}”(hŒappend="pirq=0,9,11"”h]”hŒappend="pirq=0,9,11"”…””}”hjsbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h Kehh¶hžhubhê)”}”(hŒW[value '0' is a generic 'placeholder', reserved for empty (or non-IRQ emitting) slots.]”h]”hŒ_[value ‘0’ is a generic ‘placeholder’, reserved for empty (or non-IRQ emitting) slots.]”…””}”(hj-hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Kghh¶hžhubhê)”}”(hXGenerally, 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]”hX$Generally, it’s always possible to find out the correct pirq= settings, just permute all IRQ numbers properly ... it will take some time though. An ‘incorrect’ pirq line will cause the booting process to hang, or a device won’t function properly (e.g. if it’s inserted as a module).”…””}”(hj;hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Kjhh¶hžhubhê)”}”(hŒvIf you have 2 PCI buses, then you can use up to 8 pirq values, although such boards tend to have a good configuration.”h]”hŒvIf you have 2 PCI buses, then you can use up to 8 pirq values, although such boards tend to have a good configuration.”…””}”(hjIhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Kohh¶hžhubhê)”}”(hŒGBe prepared that it might happen that you need some strange pirq line::”h]”hŒFBe prepared that it might happen that you need some strange pirq line:”…””}”(hjWhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Krhh¶hžhubjZ)”}”(hŒappend="pirq=0,0,0,0,0,0,9,11"”h]”hŒappend="pirq=0,0,0,0,0,0,9,11"”…””}”hjesbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jYhŸh³h Kthh¶hžhubhê)”}”(hŒJUse smart trial-and-error techniques to find out the correct pirq line ...”h]”hŒJUse smart trial-and-error techniques to find out the correct pirq line ...”…””}”(hjshžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Kvhh¶hžhubhê)”}”(hŒGood 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]”(hŒGood luck and mail to ”…””}”(hjhžhhŸNh Nubhô)”}”(hŒlinux-smp@vger.kernel.org”h]”hŒlinux-smp@vger.kernel.org”…””}”(hj‰hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œ mailto:linux-smp@vger.kernel.org”uh1hóhjubhŒ or ”…””}”(hjhžhhŸNh Nubhô)”}”(hŒlinux-kernel@vger.kernel.org”h]”hŒlinux-kernel@vger.kernel.org”…””}”(hjhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œ#mailto:linux-kernel@vger.kernel.org”uh1hóhjubhŒ@ if you have any problems that are not covered by this document.”…””}”(hjhžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1héhŸh³h Kxhh¶hžhubeh}”(h]”Œio-apic”ah ]”h"]”Œio-apic”ah$]”h&]”uh1h´hhhžhhŸh³h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h³uh1hŒcurrent_source”NŒ current_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¹NŒ generator”NŒ datestamp”NŒ source_link”NŒ source_url”NŒ toc_backlinks”Œentry”Œfootnote_backlinks”KŒ sectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒ strip_classes”NŒ report_level”KŒ halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ traceback”ˆŒinput_encoding”Œ utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jâŒerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œ language_code”Œen”Œrecord_dependencies”NŒconfig”NŒ id_prefix”hŒauto_id_prefix”Œid”Œ dump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h³Œ _destination”NŒ _config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒ raw_enabled”KŒline_length_limit”M'Œpep_references”NŒ pep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒ rfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œ smart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œ docinfo_xform”KŒsectsubtitle_xform”‰Œ image_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”j¼j¹sŒ nametypes”}”j¼‰sh}”j¹h¶sŒ footnote_refs”}”Œ citation_refs”}”Œ autofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ footnotes”]”Œ citations”]”Œautofootnote_start”KŒsymbol_footnote_start”KŒ id_counter”Œ collections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œ transformer”NŒ include_log”]”Œ decoration”Nhžhub.