diff options
Diffstat (limited to 'gitlab/issues_text/target_i386/host_missing/accel_KVM/2007')
| -rw-r--r-- | gitlab/issues_text/target_i386/host_missing/accel_KVM/2007 | 29 |
1 files changed, 0 insertions, 29 deletions
diff --git a/gitlab/issues_text/target_i386/host_missing/accel_KVM/2007 b/gitlab/issues_text/target_i386/host_missing/accel_KVM/2007 deleted file mode 100644 index 69e70cf49..000000000 --- a/gitlab/issues_text/target_i386/host_missing/accel_KVM/2007 +++ /dev/null @@ -1,29 +0,0 @@ -Unable to update APIC_TPR when x2APIC is enabled and -global kvm-pit.lost_tick_policy=discard parameter provided -Description of problem: -I am developing a custom OS and I wanted to implement x2APIC support. I was able to enable x2APIC, read and write some registers, like APIC_VER and APIC_SIVR. Everything looks good, except that I cannot update APIC_TPR register. Reading it always returns 0. The code I wrote works properly on bare metal. Below some observations: - -Scenario 1: -1. Enable x2APIC -2. Write to CR8 - success -3. Read from CR8 - gives correct value -4. Read from APIC_TPR - gives correct value - -Scenario 2: -1. Enable x2APIC -2. Read from APIC_TPR - gives 0 -3. Write to APIC_TPR -4. Read from APIC_TPR - gives 0 again - -Scenario 3: -1. Initialize APIC (LAPIC or xAPIC) -2. Write to APIC_TPR -3. Read from APIC_TPR - gives correct value -4. Switch to x2APIC -5. Read from APIC_TPR - gives correct value stored in pt. 2 -6. Write to APIC_TPR -7. Read from APIC_TPR - gives values stored in pt.2, not in point 6! - -Looks like APIC_TPR is stuck at value stored there before switching to x2APIC and it cannot be updated with MSR. Only update CR8 works. -I have checked parameters I passed to qemu. After removing `-global kvm-pit.lost_tick_policy=discard` problem is gone and APIC_TPR is updated correctly. -Additional information: -Please let me know if you need additional information. |