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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] CONFIG_XEN_COMPAT_030002 broken?
On 13/11/06 17:08, "Gerd Hoffmann" <kraxel@xxxxxxx> wrote: >> Yes, and to allow fewer TLB entries to be flushed when switching between >> guest kernel and guest user. That optimisation is foiled if PAGE_USER is set >> everywhere. > > Ok, so the extra cost to decide that at runtime (if > CONFIG_XEN_COMPAT_030002 is set) probably is outweighed by the tlb flush > optimization ... Definitely! The only potential problem is I don't know whether any code depends on those definitions being compile-time constant. If not, it should be a straightforward patch. By the way, the test of whether to poke in PAGE_USER can be done by looking at one of the initial mappings provided by the domain builder. If one of those ptes contains PAGE_USER, you know you need to use PAGE_USER for all kernel mappings. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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