Messages in this thread | | | Date | Wed, 8 Jun 2022 09:43:06 +0200 | From | Gerd Hoffmann <> | Subject | Re: [PATCH 0/2] Improve vfio-pci primary GPU assignment behavior |
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Hi,
> But also, this issue isn't something that only affects graphic devices, > right? AFAIU from [1] and [2], the same issue happens if a PCI device > has to be bound to vfio-pci but already was bound to a host driver.
Nope. There is a standard procedure to bind and unbind pci drivers via sysfs, using /sys/bus/pci/drivers/$name/{bind,unbind}.
> The fact that DRM happens to have some infrastructure to remove devices > that conflict with an aperture is just a coincidence.
No. It's a consequence of firmware framebuffers not being linked to the pci device actually backing them, so some other way is needed to find and solve conflicts.
> The series [0] mentioned above, adds a sysfb_disable() that disables the > Generic System Framebuffer logic that is what registers the framebuffer > devices that are bound to these generic video drivers. On disable, the > devices registered by sysfb are also unregistered.
As Alex already mentioned this might not have the desired effect on systems with multiple GPUs (I think even without considering vfio-pci).
> That is, do you want to remove the {vesa,efi,simple}fb and simpledrm > drivers or is there a need to also remove real fbdev and DRM drivers?
Boot framebuffers are the problem because they are neither visible nor manageable in /sys/bus/pci. For real fbdev/drm drivers the standard pci unbind can be used.
take care, Gerd
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