[SeaBIOS] Re: [PATCH v2 4/4] only enable 64bit pci io window when RAM >64G

[Kevin O'Connor]

On Fri, Jun 21, 2024 at 10:29:45PM +0200, Rudolf Marek wrote:
> Hi,
>
> Dne 21. 06. 24 v 15:20 Igor Mammedov napsal(a):
> > >        // Old linux kernels have trouble dealing with more than 44/46
> > >        // phys-bits. Seems to be a bug in the virtio-pci driver.
> > >        //   46:  centos-7, ubuntu-18.04
> > >        //   44:  ubuntu-16.04
> > >        // Limit the used address space to mitigate the bug, except we are
> > >        // running in a guest with more than 1TB of memory installed.
> >
> > Is it possible to fix those broken drivers (centos-7 for example)
> > and ditch this heuristic altogether?
>
> Does this code ever runs in some baremetal use cases as well?
>
> Or at least, meybe this could be applied only when virtio devices are present (maybe even just when transitional devices are present) ?

This code is only used on qemu (and derivatives) - specifically
CONFIG_QEMU must be true.  When running on coreboot, SeaBIOS expects
coreboot to map all the PCI devices.

Cheers,
-Kevin