Hi,

I'm running pv x86_64 linux under xen.

When I read the source code of the pv linux, I find that it use update_va_mapping and mmu_update to modify the page table.

However, with the writable page table mechanism, why do we need those explicit hypercalls to modify page table? In my understanding, when the guest tries to modify the page table entry, such attempts will be captured by "ptwr_do_page_fault" and then verified.

Please help to clarify my puzzle. :S