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Re: [Xen-devel] x86-64 machine_to_phys vs NX bit
| To: | Rik van Riel <riel@xxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] x86-64 machine_to_phys vs NX bit |
| From: | Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> |
| Date: | Fri, 25 Aug 2006 16:27:03 +0100 |
| Cc: | xen-devel@xxxxxxxxxxxxxxxxxxx, "Nakajima, Jun" <jun.nakajima@xxxxxxxxx> |
| Delivery-date: | Fri, 25 Aug 2006 08:27:28 -0700 |
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| Thread-topic: | [Xen-devel] x86-64 machine_to_phys vs NX bit |
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On 25/8/06 4:19 pm, "Rik van Riel" <riel@xxxxxxxxxx> wrote: >> A long is only 32 bits there, so when we pass the MFN portion the NX bit is >> conveniently truncated away! > > Which means it'll do the wrong thing for machine addresses > 4GB > on PAE, or am I overlooking something? No, it gets shifted right 12 and *then* converted to a long. So you get a 44-bit addressing capability (32+12). But NX bit is bit 63, so it gets truncated. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
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