> What else? Nothing should change for non-nvidia users who do not fall into category (a) above?
Correct, to the best of my knowledge. > How obvious is the fix for case (a), if it happens? Is there a log message that would give a hint? The user would see many log messages in dmesg indicating that the BAR was not successfully mapped due to it being too large for the allotted I/O memory region, potentially accompanied by messages from that device's driver indicating initialization failures (which would vary depending on the vendor). Ex: [ 4.729088] pci 0000:06:00.0: BAR 2 [mem size 0x2000000000 64bit pref]: can't assign; no space [ 4.731983] pci 0000:06:00.0: BAR 4 [mem size 0x02000000 64bit pref]: can't assign; no space <repeated for each impacted GPU> with Nvidia GPUs, the GPU driver will also spam the following to the console in that scenario at initialization time: [ 194.995261] NVRM: This PCI I/O region assigned to your NVIDIA device is invalid: [ 194.995261] NVRM: BAR0 is 0M @ 0x0 (PCI:0000:06:00.0) Since this would only occur for users who explicitly overrode their MMIO window size to be a lower value than PDMW, I expect that users of such a flag would understand its impact and thus would take a look at that setting first, if they found themselves in this scenario. > Can we summarize what impact this update could have on non-nvidia systems? > Let's focus on what non-nvidia users could get from this update, good or bad. The good: While I have not tested this on other vendors' GPUs personally, these same opt-in improvements should also become available to them as well with this patch, since the underlying issue is purely a function of GPU memory size. The bad: Case (a) could happen, if any user (nvidia or otherwise) has their VM configured with opt/ovmf/X-PciMmio64Mb set to a value smaller than PDMW, and also smaller than their GPU's MMIO window size. (which is, in my opinion, unlikely, since X-PciMmio64Mb < PDMW would be a config setting with no functional impact on Noble OVMF today). -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2101903 Title: Backport "OvmfPkg: Use user-specified opt/ovmf/X-PciMmio64Mb value unconditionally" to Noble To manage notifications about this bug go to: https://bugs.launchpad.net/edk2/+bug/2101903/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
