Re: [PATCH v4 1/2] cxl: Set the PBCQ Tunnel BAR register when enabling capi mode

Philippe Bergheaud [off-list ref] writes:

Skiboot used to set the default Tunnel BAR register value when capi mode
was enabled. This approach was ok for the cxl driver, but prevented other
drivers from choosing different values.

Skiboot versions > 5.11 will not set the default value any longer. This
patch modifies the cxl driver to set/reset the Tunnel BAR register when
entering/exiting the cxl mode, with pnv_pci_set_tunnel_bar().

That should work with old skiboot (since we are re-writing the value
already set) and new skiboot.

But doesn't that mean new skiboot can't boot any old kernel? That seems
undesirable.

cheers