Re: [RFC] xen/x86: allow overlaps with non-RAM regions

[Jason Andryuk <jason.andryuk@xxxxxxx>]

On 2025-04-04 04:07, Jan Beulich wrote:
> On 04.04.2025 03:01, Stefano Stabellini wrote:
> > On one Sapphire AMD x86 board, I see this:
> >
> >
> > (XEN) [0000003943ca6ff2]  [00000000f0000000, 00000000f7ffffff] (reserved)
> > (XEN) [00000039460886d9]  [00000000fd000000, 00000000ffffffff] (reserved)
> > [...]
> > (XEN) [    4.612235] 0000:02:00.0: not mapping BAR [fea00, fea03] invalid 
> > position
> I, too, see something like this on an SPR system. That's a firmware issue,
> which hence first of all should be dealt with at the firmware side.
>
> > Linux boots fine on this platform but Linux as Dom0 on Xen does not.
> > This is because the pci_check_bar->is_memory_hole check fails due to the
> > MMIO region overlapping with the EFI reserved region.
> And then what's the actual, observable problem? On my system I haven't
> noticed anything going wrong yet, albeit the affected device is also left
> without a driver.
The nvme drive (0000:02:00.0 with the invalid position above) fails to 
work and no root drive is available.
> Also aiui you strictly mean PVH Dom0 here?
I think we only looked at PVH Dom0.

Regards,
Jason