Xen devel - Apr 2009 - Xen dmesg ringbuffer

Hi,

Is there any configuration setting to increase the size of the
ringbuffer used for Xen dmesg ?

I wanted to check the advanced features supported on my Xen systems,
on my Optiplex 755 I can read the info by running "xm dmesg" and
searching for VMX:

(XEN) VMX: Supported advanced features:
(XEN)  - APIC TPR shadow
(XEN)  - MSR direct-access bitmap

But on my Supermicro system which has iommu=1
iommu_inclusive_mapping=1 set the output is lost because there is too
much other debug info being output, even if I check the dmesg
immediately after booting the system the buffer has already
overflowed.

If there is no option to configure the buffer size then at the very
least should''nt it be set big enough to hold all of the debug info
that might be output when booting Xen and dom0? once dom0 is running
the buffer can be written out to a file and cleared.

Andy

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On 14/04/2009 11:00, "Andrew Lyon" <andrew.lyon@gmail.com>
wrote:
> If there is no option to configure the buffer size then at the very
> least should''nt it be set big enough to hold all of the debug info
> that might be output when booting Xen and dom0? once dom0 is running
> the buffer can be written out to a file and cleared.
The iommu code logs large amounts of crap (still, even after I silenced a
lot of it). One way to get the list of advanced features would be do a
single boot of your Supermicro system without iommu=1.

 -- Keir



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