From 07b81ed937b37e4c1974626c38e2f192ce08f8f5 Mon Sep 17 00:00:00 2001 From: zhanghailiang Date: Fri, 29 Aug 2014 11:52:51 +0800 Subject: [PATCH] acpi-build: Set FORCE_APIC_CLUSTER_MODEL bit for FADT flags If we start Windows 2008 R2 DataCenter with number of cpu less than 8, The system will use APIC Flat Logical destination mode as default configuration, Which has an upper limit of 8 CPUs. The fault is that VM can not show all processors within Task Manager if we hot-add cpus when the number of cpus in VM extends the limit of 8. If we use cluster destination model, the problem will be solved. Note: This flag was introduced later than ACPI v1.0 specification while QEMU generates v1.0 tables only, but... linux kernel ignores this flag, so patch has no influence on it. Tested with Win[XPsp3|Srv2003EE|Srv2008DC|Srv2008R2|Srv2012R2], there isn't BSODs and guests boot just fine. In cases guest doesn't support cpu-hotplug, cpu becomes visible after reboot and in case the guest supports cpu-hotplug, it works as expected with this patch. Cc: qemu-stable@nongnu.org Signed-off-by: huangzhichao Signed-off-by: zhanghailiang Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-By: Igor Mammedov --- hw/i386/acpi-build.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index 3e7fba3822..a3133211a8 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -551,6 +551,12 @@ static void fadt_setup(AcpiFadtDescriptorRev1 *fadt, AcpiPmInfo *pm) (1 << ACPI_FADT_F_SLP_BUTTON) | (1 << ACPI_FADT_F_RTC_S4)); fadt->flags |= cpu_to_le32(1 << ACPI_FADT_F_USE_PLATFORM_CLOCK); + /* APIC destination mode ("Flat Logical") has an upper limit of 8 CPUs + * For more than 8 CPUs, "Clustered Logical" mode has to be used + */ + if (max_cpus > 8) { + fadt->flags |= cpu_to_le32(1 << ACPI_FADT_F_FORCE_APIC_CLUSTER_MODEL); + } }