Nakajima, Jun
2005-Oct-15 05:44 UTC
RE: [Xen-devel] Switching from writeable pagetabletoshadowlog-dirtyat runtime
Ian Pratt wrote:>> We found that in 32-bit code, the shadow_fault() do one more thing >> than 64-bit code. The following code in file shadow32.c checks the >> L1 page table with RW bit removed and make the shadow with RW bit, it >> does not inject the fault to guest. >> Does this is a work-around for switch from writable pagetable to >> shadow mode enable? Does this code makes sense to the writeable >> pagetable, and then may be one reason that 32bit log-dirty code can >> work? > > Yep, the code you highlight is in shadow32 to support writable > pagetable emulation when in shadow mode. > > My original shadow mode implementation didn''t need special case code > to handle writable pagetables as the shadow fault handler was called > after the writeable pagetable handler in the main page fault handler: > the writeable pagetable fault was handled but then eecution was > allowed to drop through into the shadow fault handler, propagating > the change into the shadow pagetable without having to take another > fault. It may be possible to do something similar to remove the > special case, but I''m less familiar with the current code. > > IanSo, let''s add the code to shadow.c and continue on debugging. Jun --- Intel Open Source Technology Center _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel