diff options
Diffstat (limited to 'gitlab/issues/target_arm/host_missing/accel_HVF/864.toml')
| -rw-r--r-- | gitlab/issues/target_arm/host_missing/accel_HVF/864.toml | 23 |
1 files changed, 0 insertions, 23 deletions
diff --git a/gitlab/issues/target_arm/host_missing/accel_HVF/864.toml b/gitlab/issues/target_arm/host_missing/accel_HVF/864.toml deleted file mode 100644 index 91907f99..00000000 --- a/gitlab/issues/target_arm/host_missing/accel_HVF/864.toml +++ /dev/null @@ -1,23 +0,0 @@ -id = 864 -title = "HVF virtual counter diverges from CLOCK_VIRTUAL when the host sleeps" -state = "opened" -created_at = "2022-02-10T01:36:27.240Z" -closed_at = "n/a" -labels = ["accel: HVF", "target: arm"] -url = "https://gitlab.com/qemu-project/qemu/-/issues/864" -host-os = "macOS" -host-arch = "arm64" -qemu-version = "6621441db50d5bae7e34dbd04bf3c57a27a71b32" -guest-os = "Fedora 35" -guest-arch = "aarch64" -description = """HVF's virtual counter diverges from `CLOCK_VIRTUAL` when the host sleeps and causes the inconsistency between Linux's system counter and everything else. - -HVF's virtual counter apparently relies on something similar to `mach_absolute_time`, which stops when the host sleeps and resumes after it wakes up. However, `CLOCK_VIRTUAL` is implemented with `mach_continuous_time`, which continues even while the host sleeps. Linux uses the virtual counter as the source of the system counter and sees inconsistencies between the system counter and the other devices.""" -reproduce = """1. Launch Fedora. -2. Compare the time shown at the top of the guest display and one at the top of the host display. The difference should be less than 2 minutes. -3. Let the host sleep for 3 minutes. -4. Compare the times again. The difference is now greater than 2 minutes.""" -additional = """Here are solutions I've came up with so far. There are trade-offs but any of them should be better than the current situation. I'm happy to implement one if the maintainers have decided which one is the best or figure out a superior alternative. -- Implement `cpus_get_virtual_clock` of `AccelOpsClass` with `mach_absolute_time`. It would make HVF inconsistent with the other accelerators. Linux also expects the virtual clock is "continuous" and it leaves the divergence from the real time. -- Request XNU `HOST_NOTIFY_CALENDAR_CHANGE` to update the virtual clock with the continuous time. The interface is undocumented. -- Use `IORegisterForSystemPower` to update the virtual clock with the continuous time. It is undocumented that the interface handles every cases where `mach_absolute_time` and `mach_continuous_time`, but it actually does if I read XNU's source code correctly.""" |