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SubjectRe: [PATCH 2/6] DMI: Introduce dmi_first_match to make the interface more flexible
2009/1/19 Rafael J. Wysocki <>:
> From: Rafael J. Wysocki <>
> Some notebooks from HP have the problem that their BIOSes attempt to
> spin down hard drives before entering ACPI system states S4 and S5.
> This leads to a yo-yo effect during system power-off shutdown and the
> last phase of hibernation when the disk is first spun down by the
> kernel and then almost immediately turned on and off by the BIOS.
> This, in turn, may result in shortening the disk's life times.
> To prevent this from happening we can blacklist the affected systems
> using DMI information. However, only the on-board controlles should
> be blacklisted and their PCI slot numbers can be used for this
> purpose. Unfortunately the existing interface for checking DMI
> information of the system is not very convenient for this purpose,
> because to use it, we would have to define special callback functions
> or create a separate struct dmi_system_id table for each blacklisted
> system.
> To overcome this difficulty introduce a new function
> dmi_first_match() returning a pointer to the first entry in an array
> of struct dmi_system_id elements that matches the system DMI
> information. Then, we can use this pointer to access the entry's
> .driver_data field containing the additional information, such as
> the PCI slot number, allowing us to do the desired blacklisting.
> Signed-off-by: Rafael J. Wysocki <>

Tested-by: Maciej Rutecki <>

Tested on HP Compaq nx6310

Thanks for patches

Maciej Rutecki

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