From: Andrew Jones <[email protected]> This patch is the ACPI equivalent of "hw/arm/virt: Add always-on property to the virt board timer". The timer is always on, and thus setting this informs Linux that it may switch off the periodic timer. Switching off the periodic timer substantially reduces the number of interrupts the host needs to inject.
Testing note: AArch64 guests (the only ones currently booting with ACPI) do not actually need this patch to determine it can turn the periodic timer off. I therefore used a hacked guest kernel to ensure this patch works as the equivalent DT patch does. Signed-off-by: Andrew Jones <[email protected]> Reviewed-by: Shannon Zhao <[email protected]> Message-id: [email protected] Signed-off-by: Peter Maydell <[email protected]> --- hw/arm/virt-acpi-build.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c index 87fbe7c..f6e538f 100644 --- a/hw/arm/virt-acpi-build.c +++ b/hw/arm/virt-acpi-build.c @@ -443,7 +443,7 @@ build_gtdt(GArray *table_data, GArray *linker) gtdt->secure_el1_flags = ACPI_EDGE_SENSITIVE; gtdt->non_secure_el1_interrupt = ARCH_TIMER_NS_EL1_IRQ + 16; - gtdt->non_secure_el1_flags = ACPI_EDGE_SENSITIVE; + gtdt->non_secure_el1_flags = ACPI_EDGE_SENSITIVE | ACPI_GTDT_ALWAYS_ON; gtdt->virtual_timer_interrupt = ARCH_TIMER_VIRT_IRQ + 16; gtdt->virtual_timer_flags = ACPI_EDGE_SENSITIVE; -- 1.9.1
