## page was renamed from Kernel/Reference/fwts/crs
== Firmware Test Suite - crs test ==

The _CRS test checks to see if the kernel is configuring PCI host bridge windows using the appropriate ACPI object _CRS (Current Resource Settings).  For more information on _CRS see section 6.2.2 of the ACPI reference and also arch/x86/pci/acpi.c in the kernel for the PCI host bridge configuration.

Please note:

 * The test will skipped if the machine was booted with kernel option"pci=nocrs" because the kernel was told to explicitly ignore host bridge windows _CRS settings.
 
The test will fail if:

 * The kernel cannot determine the BIOS age, so it has to assume the the BIOS is too old to correctly specify the host bridge MMIO aperture using _CRS.  One can force the use of _CRS by specifying "pci=use_crs".
 * The BIOS age is new enough, pci=nocrs is not being used but the kernel has ignored the use of _CRS for some reason.
 * The BIOS age is new enough, pci=crs is being used unnecessarily and the kernel is using _CRS.
 
Otherwise the test will pass the machine's configuration.

=== Examples: ===

{{{
sudo fwts crs - 
}}}

..runs the test on your machine and dumps the output to stdout.

{{{
sudo fwts crs
}}}

..runs the test on your machine and appends the output to the default log results.log.

== Explanation of test results ==

Certain test results may require a little more explanation. This section will try and give some context to specific test failures.

||Error ID||Explanation||
||BIOS``Too``Old||BIOS was made before 2008 and is tool old to probably support this feature.||
||BIOS``No``Release``Date||Kernel could not determine the age of the BIOS.||
||BIOS``Support``Bridge``Windows||BIOS supports _CRS bridge windows, but has been booted with pci=use_crs which is unnecessary and can be removed.||