The `pci=' argument (not avail. in v2.0 kernels) can be used to change the behaviour of PCI bus device probing and device behaviour. Firstly the file
linux/drivers/pci/pci.c checks for architecture independent
pci= options. The remaining allowed arguments are handled in
linux/arch/???/kernel/bios32.c and are listed below for ???=i386.
These are used to set/clear the flag indicating that the PCI probing is to take place via the PCI BIOS. The default is to use the BIOS.
If PCI direct mode is enabled, the use of these enables either configuration Type 1 or Type 2. These implicitly clear the PCI BIOS probe flag (i.e. `pci=nobios') too.
If you get a message like
PCI: Unassigned IO space for.../ then you may need to supply an I/O value with this option. From the source:
``Several BIOS'es forget to assign addresses to I/O ranges. We try to fix it here, expecting there are free addresses starting with
0x5800. Ugly, but until we come with better resource management, it's the only simple solution.''
This disables the default peer bridge fixup, which according to the source does the following:
``In case there are peer host bridges, scan bus behind each of them. Although several sources claim that the host bridges should have header type 1 and be assigned a bus number as for PCI2PCI bridges, the reality doesn't pass this test and the bus number is usually set by BIOS to the first free value.''
Using this argument instructs the kernel to not sort the PCI devices during the probing phase.
Using this option disables all PCI bus probing. Any device drivers that make use of PCI functions to find and initialize hardware will most likely fail to work.
This option will reverse the ordering of the PCI devices on that PCI bus.