Martin Schwidefsky wrote > The discard fault happens on access to a volatile that has been > discarded. An important property of the s390 architecture comes into > play here: there are two page tables, a guest page table and a host page > table. What the guest perceives as its "physical" memory is in virtual > storage for the host. An address resolution has to walk two pages > tables, if a pte is invalid in either table you get a fault. A guest > fault if the invalid pte is in the guest table and a host fault if it is > Yes, I'm familiar with that trick. Wasn't sure if you had it in hardware or not. > in the host table. That gives s390 a simple method to implement > discarded pages: the hypervisor just unmaps the page from the host table > and changes the state of the guest page. I can see that you will have a > much harder time to implement this on i386. > Nah, I think we'll do just fine. Thanks for the info - based on this, I think we can probably use the volatile page / swap cache changes as well for VMware, also pretty much unchanged. Sorry to take so long to look at these patches, BTW - I was on holiday for two weeks. Zach
