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Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture
From: |
Laszlo Ersek |
Subject: |
Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture |
Date: |
Wed, 17 Jun 2020 15:26:14 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0 Thunderbird/52.9.1 |
On 06/17/20 08:40, Gerd Hoffmann wrote:
> Hi,
>
>> What if then we have OVMF relying in the physbits *iff*
>> "-host-phys-bits" is used
>
> How can the guest know?
Exactly!
> Adding "you can trust physbits" bits somewhere (as suggested by Eduardo)
> would work for sure, but would depend on a qemu update.
>
> Maybe a "don't trust physbits in case it is 40" heuristic works well
> enough in practice.
... for how many years? ;)
No heuristics please.
(I absolutely prefer X-PciMmio64Mb to guesswork. With X-PciMmio64Mb,
users at least know they have to be careful. I know they don't like
that, they just want a promise "it will work forever", but it's not
randomly called "experimental", we're not there just yet.)
Thank you,
Laszlo
>> Now, regarding the problem "to trust or not" in the guests' physbits,
>> I think it's an orthogonal discussion to some extent.
>
> It isn't. OVMF can't ignore the problem, you risk to break guests if
> you do.
>
> take care,
> Gerd
>
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, (continued)
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Daniel P . Berrangé, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Dr. David Alan Gilbert, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Eduardo Habkost, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Guilherme Piccoli, 2020/06/16
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Gerd Hoffmann, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Laszlo Ersek, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture,
Laszlo Ersek <=
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Laszlo Ersek, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Guilherme Piccoli, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Laszlo Ersek, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Guilherme Piccoli, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Laszlo Ersek, 2020/06/18
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Dr. David Alan Gilbert, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Eduardo Habkost, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Guilherme Piccoli, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Eduardo Habkost, 2020/06/17
- Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture, Guilherme Piccoli, 2020/06/17