Re: [Xen-devel] Xen not working with stock Debian Wheezy 3.2 kernel on a Core 2 Duo box

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.07.13 at 12:31, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:

$subject is probably the wrong way round, since ...

> (XEN)  0000000000000000 - 000000000008f000 (usable)
> (XEN)  000000000008f000 - 00000000000a0000 (reserved)
> (XEN)  00000000000e0000 - 0000000000100000 (reserved)
> (XEN)  0000000000100000 - 00000000ce69a000 (usable)
> (XEN)  00000000ce69a000 - 00000000ce6f1000 (ACPI NVS)
> (XEN)  00000000ce6f1000 - 00000000cf5fb000 (usable)
> (XEN)  00000000cf5fb000 - 00000000cf608000 (reserved)
> (XEN)  00000000cf608000 - 00000000cf6a5000 (usable)
> (XEN)  00000000cf6a5000 - 00000000cf6aa000 (ACPI data)
> (XEN)  00000000cf6aa000 - 00000000cf6ab000 (usable)
> (XEN)  00000000cf6ab000 - 00000000cf6f2000 (ACPI NVS)
> (XEN)  00000000cf6f2000 - 00000000cf6ff000 (ACPI data)
> (XEN)  00000000cf6ff000 - 00000000cf700000 (usable)
> (XEN)  00000000cf700000 - 00000000d0000000 (reserved)
> (XEN)  00000000fff00000 - 0000000100000000 (reserved)
> (XEN)  0000000100000000 - 0000000228000000 (usable)
> (XEN)  0000000228000000 - 000000022c000000 (unusable)

.. this and ...

> [    0.000000]  Xen: 0000000000000000 - 000000000008f000 (usable)
> [    0.000000]  Xen: 000000000008f000 - 0000000000100000 (reserved)
> [    0.000000]  Xen: 0000000000100000 - 00000000ce69a000 (usable)
> [    0.000000]  Xen: 00000000ce69a000 - 00000000ce6f1000 (ACPI NVS)
> [    0.000000]  Xen: 00000000ce6f1000 - 00000000cf5fb000 (usable)
> [    0.000000]  Xen: 00000000cf5fb000 - 00000000cf608000 (reserved)
> [    0.000000]  Xen: 00000000cf608000 - 00000000cf6a5000 (usable)
> [    0.000000]  Xen: 00000000cf6a5000 - 00000000cf6aa000 (ACPI data)
> [    0.000000]  Xen: 00000000cf6aa000 - 00000000cf6ab000 (usable)
> [    0.000000]  Xen: 00000000cf6ab000 - 00000000cf6f2000 (ACPI NVS)
> [    0.000000]  Xen: 00000000cf6f2000 - 00000000cf6ff000 (ACPI data)
> [    0.000000]  Xen: 00000000cf6ff000 - 00000000cf700000 (usable)
> [    0.000000]  Xen: 00000000cf700000 - 00000000d0000000 (reserved)
> [    0.000000]  Xen: 00000000fee00000 - 00000000fee01000 (reserved)
> [    0.000000]  Xen: 00000000fff00000 - 0000000100000000 (reserved)
> [    0.000000]  Xen: 0000000100000000 - 0000000228000000 (usable)
> [    0.000000]  Xen: 0000000228000000 - 000000022c000000 (unusable)

... this show that the kernel should be well aware that it shouldn't
map (or use in any other way) this region.

> [    0.000000] init_memory_mapping: 0000000000000000-00000000cf700000
> [    0.000000] init_memory_mapping: 0000000100000000-0000000228000000
> [    0.000000] init_memory_mapping: 0000000228000000-000000022c000000

Yet it does, ...

> (XEN) mm.c:783:d0 Non-privileged (0) attempt to map I/O space 00228000
> (XEN) mm.c:1219:d0 Failure in alloc_l1_table: entry 0
> (XEN) mm.c:2096:d0 Error while validating mfn 226221 (pfn 1e9760) for type 
> 1000000000000000: caf=8000000000000003 taf=1000000000000001
> (XEN) mm.c:2992:d0 Error while pinning mfn 226221

... and Xen rightfully rejects the attempt.

One question of course is where this pretty unusual "unusable"
memory block comes from on that system. Is this block visible the
same way when booting a native kernel, or is this being forced to
"unusable" by Xen?

Jan


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