Re: Kernel requires x86-64 CPU, after modifying arch_shared_info struct

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, Jun 29, 2020 at 07:43:43AM +0000, Jan Ruh wrote:
> 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.".

Did you try backing up your changes and seeing if the same happens?

Did you rebuild both the Xen hypervisor and the tools?

> 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?

Pasting your xl config file would be helpful in order to help debug.

> Is my
> approach to extend the arch_shared_info wrong in the first place?

Doesn't look directly related to a change in arch_shared_info IMO, but
it's hard to tell without having more info.

Posting your changes might also help spot something wonky.

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Nit: posting confidentiality banners to a public mailing lists
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Roger.