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Re: [RFC PATCH] x86/xen: Consider Xen PVH support in CONFIG_XEN_PVHVM


  • To: Teddy Astie <teddy.astie@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Tue, 24 Feb 2026 12:01:29 +0100
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  • Cc: Juergen Gross <jgross@xxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
  • Delivery-date: Tue, 24 Feb 2026 11:01:42 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 24.02.2026 11:51, Teddy Astie wrote:
> It's currently possible to build Linux with CONFIG_PVH|CONFIG_XEN_PVHVM
> and no CONFIG_XEN_PVH.

In which case, how can you expect Xen PVH to work?

> That leads to inconsistent kernels that fails with
> "Missing xen PVH initialization" when booting using PVH boot method or
> display various errors and fail to initialize Xen PV drivers when booting
> with PVH-GRUB.
> 
>     platform_pci_unplug: Xen Platform PCI: unrecognised magic value
>     ...
>     # modprobe xen-blkfront
>     modprobe: ERROR: could not insert 'xen_blkfront': No such device
>     # modprobe xen-netfront
>     modprobe: ERROR: could not insert 'xen_netfront': No such device
> 
> When built without CONFIG_XEN_PVH, PVH-specific logic is disabled, hence when
> booting with e.g PVH-OVMF, Linux assumes we are a HVM guest, even when we 
> aren't
> actually one (in the "with HVM emulated devices" sense).
> 
> As it is actually possible to boot Xen PVH without CONFIG_PVH; and that most
> Xen-related logic exist within CONFIG_XEN_PVHVM; consider PVH guests support
> within CONFIG_XEN_PVHVM instead of CONFIG_XEN_PVH.

XEN_PVHVM serves a different purpose though, iirc.

Jan



 


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