[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Enable virtual memory for Mini-os on ARM
karim.allah.ahmed@xxxxxxxxx, le Mon 23 Dec 2013 12:52:44 +0000, a écrit : > On Mon, Dec 23, 2013 at 10:38 AM, Samuel Thibault > <samuel.thibault@xxxxxxxxxxxx > > wrote: > > karim.allah.ahmed@xxxxxxxxx, le Mon 23 Dec 2013 10:23:01 +0000, a écrit : > > Why do I need to create pagetables and fill them for mini-os ? > > I don't know the virtual memory of ARM, but on x86 we definitely need a > pagetable because very often we need to map/unmap things, like granted > mfns, i/o areas, foreign pages, etc. > > Can you please refer me to the part of the code related to any of these cases > ? Essentially everything that calls map_frames and friends. - mini-os/gnttab.c calls gnttab_table = map_frames(frames, NR_GRANT_FRAMES);. - I/O can be seen in mini-os/lib/sys.c: map_frames_ex(&first_mfn, n, 0, 1, 1, DOMID_IO, NULL, _PAGE_PRESENT|_PAGE_RW); - foreign pages can be seen in tools/libxc/xc_minios.c in minios_privcmd_map_foreign_* > In ARM MMU is virtualized in HW. So you've an extra level of translation > that's > controlled by the hypervisor. > So, Is there a reason for doing map/unmap on virtual address space not on > physical one ? The physical one might be enough, I don't know the details of ARM memory to be able to tell for sure. > 1- Isolation between different entities ( processes ) - ( Is that applicable > to > mini-os ? It is not. > 2- creating a contiguous mapping of scattered pages. Which can perhaps be done at the physical layer? Samuel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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