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Re: [Xen-devel] auto_translated_physmap in Fedora

To: Pete Zaitcev <zaitcev@xxxxxxxxxx>
Subject: Re: [Xen-devel] auto_translated_physmap in Fedora
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 10 Jul 2006 12:44:24 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, quintela@xxxxxxxxxx
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On 7 Jul 2006, at 03:07, Pete Zaitcev wrote:

I noticed one curious thing while working on some issues with Fedora.
At least in 2.6.17-1.2302_FC6xen, the following evaluates to false:

        if (xen_feature(XENFEAT_auto_translated_physmap))
                return pfn;

But the head-xen.S looks like this:

.section __xen_guest
        .ascii  "GUEST_OS=linux,GUEST_VER=2.6"
        .ascii  ",XEN_VER=xen-3.0"
        .ascii  ",VIRT_BASE=0x"; utoh __START_KERNEL_map
.ascii ",HYPERCALL_PAGE=0x"; utoh (phys_hypercall_page >> PAGE_SHIFT)
        .ascii  ",FEATURES=writable_page_tables"
        .ascii           "|writable_descriptor_tables"
        .ascii           "|auto_translated_physmap"
        .ascii           "|supervisor_mode_kernel"
        .ascii  ",LOADER=generic"
        .byte   0

Everything continues to work just fine, thanks to runtime checks
of xen_feature() like the above.

The header includes 'auto_translated_physmap' indicating that the guest can handle that feature, but does not require it to be enabled.

 -- Keir

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