NAME

pcibios — introduction to PCI BIOS support

SYNOPSIS

options PCIBIOS
options PCIBIOSVERBOSE
#options PCIBIOS_IRQS_HINT=0x0a00 #IRQ 9,11
#options PCIBIOS_INTR_FIXUP_FORCE
options PCIBIOS_INTR_GUESS
#options PCIINTR_DEBUG

INTRODUCTION

pcibios provides support for setting up PCI controllers, bridges, and devices using information extracted from the BIOS.

Ideally, the boot firmware of a machine (a.k.a. BIOS) should set up all PCI devices; assigning them I/O and memory addresses and interrupts. Alas, this does not always happen, so there is some PC specific code that can do the initialization when NetBSD boots.

Options:

PCIBIOS

turn on the PCI BIOS support.

PCIBIOSVERBOSE

make the setup procedure verbose.

PCIBIOS_IRQS_HINT

hint for IRQ use. When PCI_INTR_FIXUP cannot guess an adequate IRQ for a device, the hint is used.

The value is a logical or of power-of-2s of allowable interrupts:

IRQ Value	IRQ Value	IRQ Value	IRQ Value
0 0x0001	4 0x0010	8 0x0100	12 0x1000
1 0x0002	5 0x0020	9 0x0200	13 0x2000
2 0x0004	6 0x0040	10 0x0400	14 0x4000
3 0x0008	7 0x0080	11 0x0800	15 0x8000

For example, “options PCIBIOS_IRQS_HINT=0x0a00” allows IRQ 9 and IRQ 11.

The kernel global variable pcibios_irqs_hint holds this value, so a user can override this value without kernel recompilation. For example:

• To specify this value on the fly, type the following command at the boot prompt to drop into DDB (the in-kernel debugger; you have to specify “options DDB” to make kernel with DDB):

  boot -d

  And type the following command on “db>” prompt:

  write pcibios_irqs_hint 0x0a00

  Then type the following to continue to boot:

  c

• To modify kernel image without kernel recompilation, run the following command on shell:

  gdb --write /netbsd

  And type the following commands at the “(gdb)” prompt:

  set pcibios_irqs_hint=0xa00

  quit

PCIBIOS_INTR_FIXUP_FORCE

Some buggy BIOS implementations provide inconsistent information between the PCI Interrupt Configuration Register and the PCI Interrupt Routing table. In such case, the PCI Interrupt Configuration Register takes precedence by default. If this happens, a kernel with PCIBIOSVERBOSE shows “WARNING: preserving irq XX” in the PCI routing table.

If PCIBIOS_INTR_FIXUP_FORCE is specified in addition to the PCI_INTR_FIXUP, the PCI Interrupt Routing table takes precedence. In this case, a kernel with PCIBIOSVERBOSE shows “WARNING: overriding irq XX” in the PCI routing table.

PCIBIOS_INTR_GUESS

make PCI_INTR_FIXUP work with unknown interrupt router.

If a PCI interrupt router is not known, normally interrupt configuration will not be touched.

But if PCIBIOS_INTR_GUESS is specified in addition to the PCI_INTR_FIXUP, and if a PCI interrupt routing table entry indicates that only one IRQ is available for the entry, the IRQ is assumed to be already connected to the device, and corresponding PCI Interrupt Configuration Register will be configured accordingly.

PCIINTR_DEBUG

make the PCI_INTR_FIXUP procedure verbose.

SEE ALSO

cardbus(4), pci(4)

HISTORY

The pcibios code appeared in NetBSD 1.5.

BUGS

The PCIBIOS_ADDR_FIXUP option may conflict with the PCI CardBus driver's own address fixup.