Kernel requires x86-64 CPU, after modifying arch_shared_info struct

[Jan Ruh <jan.ruh@xxxxxxxxxx>]

Hi Xen Dev Community,

I ran into an issue when implementing a prototype for a new paravirtualized clock for x86-64 hosts. I extended the arch_shared_info struct by 6 fields totaling at 36 bytes. I updated the xen-foreign/references.size to represent the new size of the arch_shared_info struct. The fields are correctly updated in Xen and I am also able to read the correct information stored from dom0. However, if I try to start a hvm VM with pvh extensions it does not boot telling me that "This kernel requires an x86-64 CPU, but only detected an i686 CPU.". I have rebuild my Linux domU kernel just as the dom0 kernel and everything should be compatible. To me this looks like Xen or libxc does some compatibility checks before booting up my HVM domU and decides to downgrade the detectable CPU due to some issue that I am not aware of. Do I miss something? Is my approach to extend the arch_shared_info wrong in the first place? I am really thankful for some advice or pointers what is happening here.

Best

Jan

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