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| author | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
|---|---|---|
| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
| commit | 4b927bc37359dec23f67d3427fc982945f24f404 (patch) | |
| tree | 245449ef9146942dc7fffd0235b48b7e70a00bf2 /gitlab/issues/target_missing/host_missing/accel_missing/2705.toml | |
| parent | aa8bd79cec7bf6790ddb01d156c2ef2201abbaab (diff) | |
| download | emulator-bug-study-4b927bc37359dec23f67d3427fc982945f24f404.tar.gz emulator-bug-study-4b927bc37359dec23f67d3427fc982945f24f404.zip | |
add gitlab issues in toml format
Diffstat (limited to 'gitlab/issues/target_missing/host_missing/accel_missing/2705.toml')
| -rw-r--r-- | gitlab/issues/target_missing/host_missing/accel_missing/2705.toml | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/gitlab/issues/target_missing/host_missing/accel_missing/2705.toml b/gitlab/issues/target_missing/host_missing/accel_missing/2705.toml new file mode 100644 index 00000000..76efed16 --- /dev/null +++ b/gitlab/issues/target_missing/host_missing/accel_missing/2705.toml @@ -0,0 +1,29 @@ +id = 2705 +title = "USB event delivery does not work correctly for macOS guests with XHCI controller without MSI(-X)" +state = "closed" +created_at = "2024-12-01T15:45:07.801Z" +closed_at = "2025-03-06T05:32:11.312Z" +labels = ["USB", "hostos: macOS"] +url = "https://gitlab.com/qemu-project/qemu/-/issues/2705" +host-os = "Any" +host-arch = "x86-64, aarch64" +qemu-version = "9.2.0-rc2" +guest-os = "macOS" +guest-arch = "x86-64, aarch64" +description = "n/a" +reproduce = """1. Get a macOS VM working. Either on x86-64 with a Q35 machine type, AppleSMC device, and OpenCore bootloader, or on aarch64 using the patch set and instructions linked above. +2. On x86-64, switch to a NEC XHCI controller with MSI and MSI-X support forcibly disabled: `-device nec-usb-xhci,id=xhci,msi=off,msix=off` +3. Boot macOS. + +USB events are now extremely laggy. A USB keyboard or mouse becomes almost unusable. + + +While narrowing down the problem, I established the following facts by experimentation, tracing, and code inspection: + + * Although the vmapple platform uses an emulated XHCI PCI device for connecting virtual USB devices, it does not support message-signalled interrupts, in either the MSI or MSI-X persuasion. (This is true in Apple's implementation as well, but the macOS guest's XHCI driver unsurprisingly does work with Apple's PCI/XHCI implementation.) + * macOS guests (and the iBoot bootloader) appear to refuse to drive XHCI controllers with `numintrs < 4`, for both aarch64 and x86-64 architectures. They will generally set up event rings 0, 1, and 2. + * QEMU's PCI XHCI implementation does not appear to implement (as of 9.2.0-rc2) any mitigations for when the controller is used in pin-based IRQ mode. It will happily attempt to use event rings >0 in this case, but interrupts are dropped. + * Linux and FreeBSD guests appear to use only interrupter 0 anyway, so these are not useful references. + +It's not entirely clear to me what component is ultimately responsible for the failure here - I suspect there might be some not-quite-right behaviour in both macOS's XHCI driver and Qemu's XHCI implementation, and that these conspire to a non-functional setup.""" +additional = "n/a" |