RE: [Xen-devel] KernelBUGatarch/x86_64/mm/../../i386/mm/hypervisor.c:197

[Christophe Saout <christophe@xxxxxxxx>]

Am Donnerstag, den 05.10.2006, 05:02 +0100 schrieb Ian Pratt:

> Glad it works for you, but I wish we understood what was going on a bit
> more. It may be that the bios is just borked and the e820 map it gives
> xen misses some regions that it steals for other purposes. It would be
> pretty surprising if Xen had bugs in its e820 code. 
> 
> It might be interesting to post the xm dmesg output with the two
> different BIOS settings to see if there's anything unusual about the
> e820 map.

The only difference is in the Physical RAM map:

Broken (with memory hole remapping turned on):

(XEN) Physical RAM map:
(XEN)  0000000000000000 - 000000000009fc00 (usable)
(XEN)  000000000009fc00 - 00000000000a0000 (reserved)
(XEN)  00000000000e8000 - 0000000000100000 (reserved)
(XEN)  0000000000100000 - 00000000bfff0000 (usable)
(XEN)  00000000bfff0000 - 00000000bffff000 (ACPI data)
(XEN)  00000000bffff000 - 00000000c0000000 (ACPI NVS)
(XEN)  00000000ff780000 - 0000000100000000 (reserved)
(XEN)  0000000100000000 - 000000030e000000 (usable)
(XEN) System RAM: 11487MB (11763260kB)

Working (with memory hole remapping turned off):

(XEN) Physical RAM map:
(XEN)  0000000000000000 - 000000000009fc00 (usable)
(XEN)  000000000009fc00 - 00000000000a0000 (reserved)
(XEN)  00000000000e8000 - 0000000000100000 (reserved)
(XEN)  0000000000100000 - 00000000efff0000 (usable)
(XEN)  00000000efff0000 - 00000000effff000 (ACPI data)
(XEN)  00000000effff000 - 00000000f0000000 (ACPI NVS)
(XEN)  00000000ff780000 - 0000000100000000 (reserved)
(XEN)  0000000100000000 - 0000000300000000 (usable)
(XEN) System RAM: 12031MB (12320316kB)

The strange thing is that the upper configuration shows even less memory
that the second one which has only 256MB missing?

>  Might be worth comparing against what Linux prints too.

Ok, I'll try to boot the Dom0 without hypervisor to get some numbers
from native Linux for comparison.

As Keir suggested, this really might be a BIOS bug. Our hardware vendor
has notified the motherboard manufacturer to have this checked (this
already was the latest version).



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