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Diffstat (limited to 'Documentation/virtual/kvm/devices/arm-vgic.txt')
| -rw-r--r-- | Documentation/virtual/kvm/devices/arm-vgic.txt | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt index 76e61c883347..b2f60ca8b60c 100644 --- a/Documentation/virtual/kvm/devices/arm-vgic.txt +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt @@ -83,6 +83,12 @@ Groups: Bits for undefined preemption levels are RAZ/WI. + For historical reasons and to provide ABI compatibility with userspace we + export the GICC_PMR register in the format of the GICH_VMCR.VMPriMask + field in the lower 5 bits of a word, meaning that userspace must always + use the lower 5 bits to communicate with the KVM device and must shift the + value left by 3 places to obtain the actual priority mask level. + Limitations: - Priorities are not implemented, and registers are RAZ/WI - Currently only implemented for KVM_DEV_TYPE_ARM_VGIC_V2. |