| Message ID | 1453380893-26174-1-git-send-email-drjones@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 2016/1/21 20:54, Andrew Jones wrote: > 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. > Reviewed-by: Shannon Zhao <shannon.zhao@linaro.org> > Signed-off-by: Andrew Jones <drjones@redhat.com> > --- > 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 87fbe7c97d99b..f6e538f3d02ea 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; >
On 21 January 2016 at 12:54, Andrew Jones <drjones@redhat.com> wrote: > 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 <drjones@redhat.com> Applied to target-arm.next, thanks. -- PMM
diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c index 87fbe7c97d99b..f6e538f3d02ea 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;
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 <drjones@redhat.com> --- hw/arm/virt-acpi-build.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)