Re: [Xen-users] Extra Probes on xl create

[Ian <murrayie@xxxxxxxxxxx>]

On 30/05/12 06:44, Ian Campbell wrote:
> On Wed, 2012-05-30 at 01:15 +0100, Ian wrote:
> > Hi All,
> >
> > I have two Xen machines, both running 4.12 compiled from source. One is
> > running SL6.2 with a kernel compiled from vanilla source (3.2.0) and the
> > second is using the stock kernel from Ubuntu (3.2.0-23-generic).
> >
> > I moved a pv CentOS 5.8 vm from the SL machine to the Ubuntu machine and
> > noticed a difference when starting (i.e. an error)
> >
> > "xl -v create" gives...
> >
> >
> > SL 6.2
> >
> > domainbuilder: detail: xc_dom_allocate: cmdline="ro root=LABEL=/
> > console=xvc0 ", features="(null)"
> > domainbuilder: detail: xc_dom_kernel_mem: called
> > domainbuilder: detail: xc_dom_malloc            : 10836 kB
> > domainbuilder: detail: xc_dom_do_gunzip: unzip ok, 0x21bbf4 ->  0xa952d8
> > domainbuilder: detail: xc_dom_ramdisk_mem: called
> > domainbuilder: detail: xc_dom_boot_xen_init: ver 4.1, caps
> > xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p
> > hvm-3.0-x86_64
> > domainbuilder: detail: xc_dom_parse_image: called
> > domainbuilder: detail: xc_dom_find_loader: trying ELF-generic loader ...
> > domainbuilder: detail: loader probe OK
> >
> > Ubuntu 12.04
> >
> > domainbuilder: detail: xc_dom_allocate: cmdline="ro root=LABEL=/
> > console=xvc0 ", features="(null)"
> > domainbuilder: detail: xc_dom_kernel_mem: called
> > domainbuilder: detail: xc_dom_malloc            : 10836 kB
> > domainbuilder: detail: xc_dom_do_gunzip: unzip ok, 0x21bbf4 ->  0xa952d8
> > domainbuilder: detail: xc_dom_ramdisk_mem: called
> > domainbuilder: detail: xc_dom_boot_xen_init: ver 4.1, caps
> > xen-3.0-x86_64 xen-3.0-x86_32p
> > domainbuilder: detail: xc_dom_parse_image: called
> > domainbuilder: detail: xc_dom_find_loader: trying multiboot-binary
> > loader ...
> > domainbuilder: detail: loader probe failed
> > domainbuilder: detail: xc_dom_find_loader: trying Linux bzImage loader ...
> > xc: error: panic: xc_dom_bzimageloader.c:556:
> > xc_dom_probe_bzimage_kernel: kernel is not a bzImage: Invalid kernel
> > domainbuilder: detail: loader probe failed
> > domainbuilder: detail: xc_dom_find_loader: trying ELF-generic loader ...
> > domainbuilder: detail: loader probe OK
> >
> >
> > Both boot fine, and it looks like the Ubuntu version is trying to do
> > something extra. I googled the error message and I am not concerned
> > about it as it appears to be a spurious error caused by an extra probe.
After further digging, it would seem that the SL machine was performing 
the same actions. Further digging in the source code suggests that the 
loaders are "pluggable" and are "registered". Fair to say that for some 
reason, they are registered in a different order on the different 
machines. Most of this stretches my limited understanding of C and I am 
not figuring out how the ordering of the registration is done. Maybe the 
compiler, maybe make.
I am starting to think this isn't worth worrying about.



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