On Mon, Feb 23, 2009 at 04:59:37PM +0200, Avi Kivity wrote: > Marcelo Tosatti wrote: >>> Thanks for your fast answer and for your help for debugging. >>> >> >> If you confirm that FreeBSD is indeed relying on cr3 to sync global >> pages, it might be better to disable the optimization. Lets hope that is >> not the case. >> > > cr3 writes explicitly do not flush global pages; otherwise what would be > the point of global pages at all? >From the Intel TLB doc: The processor is always free to invalidate additional entries in the TLBs and paging-structure caches. The following are some examples: • MOV to CR3 may invalidate TLB entries for global pages. The reasoning was if an optimization breaks an important guest which contains a bug that happens to not trigger on real HW due to positioning of the stars, it is reasonable to disable that optimization. > In other words, the only difference between global and non-global pages > is visible via cr3 writes. -- 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
