On 17/07/12 00:17, Jaikumar G wrote: > Hi Ram, > > Thanks that makes a lot of sense. > > Regarding allocation of memory in guest space: > > "QEMU has a feature where it can translate a guest virtual address in > user space directly into the corresponding physical/backing page in RAM > without the need for allocating memory in Guest space." > > Is is something that can be done in virtual box ? Is there any > significant performance differences ? >
I don't know the context of that quote or what feature it refers to. As far as VirtualBox is concerned, we could classify this into 2 cases for the sake of simplicity. 1. Without Nested Paging (NP) / Extended Page Tables (EPT): the hypervisor traps #PFs in the guest and syncs its shadow page tables. Host-side translation of guest addresses is done by traversing the shadow page tables. 2. With NP/EPT: #PFs in the guest are handled without causing VM-exits as the hardware supports an extra indirection of address translation. The host TLBs can cache guest linear addresses to host physical addresses. VirtualBox fully supports NP/EPT if the hardware has support for it. Regards, Ram. _______________________________________________ vbox-dev mailing list [email protected] https://www.virtualbox.org/mailman/listinfo/vbox-dev
