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:
For example, "options PCIBIOS_IRQS_HINT=0x0a00" allows IRQ 9 and IRQ 11.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 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):
And type the following command on "db>" prompt:
boot -dThen type the following to continue to boot:write pcibios_irqs_hint 0x0a00c - To modify kernel image without kernel recompilation, run the following
command on shell:
And type the following commands at the "(gdb)" prompt:
gdb --write /netbsdset pcibios_irqs_hint=0xa00quit
- 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):
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
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.