ACPI: BIOS _OSI(Linux) query ignored -- PowerEdge 2900

ACPI: EC: Look up EC in DSDT
ACPI: BIOS _OSI(Linux) query ignored
ACPI: DMI System Vendor: Dell Inc.
ACPI: DMI Product Name: PowerEdge 2900
ACPI: DMI Product Version:
ACPI: DMI Board Name: 0NX642
ACPI: DMI BIOS Vendor: Dell Inc.
ACPI: DMI BIOS Date: 09/12/2008
ACPI: Please send DMI info above to [email protected]
ACPI: If "acpi_osi=Linux" works better, please notify [email protected]

When add acpi_osi=Linux, it shows:
BIOS _OSI(Linux) query honored via cmdline
DMI System Vendor: Dell Inc.
DMI Product Name: PowerEdge 2900
DMI Product Version:
DMI Board Name: 0NX642
DMI BIOS Vendor: Dell Inc.
DMI BIOS Date: 09/12/2008
Please send DMI info above to [email protected]

output of acpidump included.