On Mon, May 18, 2009 at 08:53:58AM +0300, Gleb Natapov wrote: > 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. It didn't. History shows that this method is what is used in some unisys machines, which seems to be the only ones implementing this around. -- 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
