On Mon, May 18, 2009 at 08:44:54AM +0300, Avi Kivity wrote: > Gleb Natapov wrote: >> On Sun, May 17, 2009 at 11:07:31PM +0300, Avi Kivity wrote: >> >>> Gleb Natapov wrote: >>> >>>> Theoretically we can provide different values for different OSes, but >>>> this is just a guess work since there is no any documentation how CPU >>>> hot-plug should work on x86. >>>> >>> ACPI in fact supports this, but I hope we don't have to do that. >>> >>> >> ACPI way is what I am talking about. Implement _OS object. >> > > /* > * The story of _OSI(Linux) > * > * From pre-history through Linux-2.6.22, > * Linux responded TRUE upon a BIOS OSI(Linux) query. > * > * Unfortunately, reference BIOS writers got wind of this > * and put OSI(Linux) in their example code, quickly exposing > * this string as ill-conceived and opening the door to > * an un-bounded number of BIOS incompatibilities. > * > * For example, OSI(Linux) was used on resume to re-POST a > * video card on one system, because Linux at that time > * could not do a speedy restore in its native driver. > * But then upon gaining quick native restore capability, > * Linux has no way to tell the BIOS to skip the time-consuming > * POST -- putting Linux at a permanent performance disadvantage. > * On another system, the BIOS writer used OSI(Linux) > * to infer native OS support for IPMI! On other systems, > * OSI(Linux) simply got in the way of Linux claiming to > * be compatible with other operating systems, exposing > * BIOS issues such as skipped device initialization. > * > * So "Linux" turned out to be a really poor chose of > * OSI string, and from Linux-2.6.23 onward we respond FALSE. > * > * BIOS writers should NOT query _OSI(Linux) on future systems. > * Linux will complain on the console when it sees it, and return FALSE. > * To get Linux to return TRUE for your system will require > * a kernel source update to add a DMI entry, > * or boot with "acpi_osi=Linux" > */ > > // Looks like no real content in this message? > Now I recall something on LKML about this. Well, in this case Linux shouldn't have used ACPI to invent its own way to do cpu hot-plug. Interesting whether _OSI(Windows) will evaluate to TRUE on Linux. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
