[coreboot] AMG G-series - Steppe eagle - PCI IRQ Routing to 8259 PIC

Rudolf Marek r.marek at assembler.cz
Sun Nov 5 21:08:50 CET 2017

Hi Abhishek,

Please can you check if you programmed the ELCR registers 0x4d0/0x4d1
to level for PCI registers?

In other words, you should set bits to 1 to corresponding IRQ to be level
triggered. Eg. for IRQ 5, you need to write 1 to bit5 to 8bit I/O port 0x4d0 For
IRQ 9, you need to program bit 1 of 0x4d1

You can also check the PCI status register (reg  of Ethernet device, there is
"interrupt pending" bit, to verify that the device actually tries to trigger the
IRQ. Also, you can check if INTX disable is not set in PCI register by accident.

lspci -vvv
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping-
SERR- FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort-

You should see  DisINTx- and INTx+ (if interrupt is pending).

The local APIC has also individual vector interrupt disable bits (but you say
local apic is disabled, normally for te local APIC should have programmed EXTINT
mode on LINT0, or virtual wire in IOAPIC)

Has this platform more than 1 IOAPIC, or just IOAPIC in SB?


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