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:
-
-
- 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.