When running QEMU without -cpu parameter, the user usually wants a sane
default. So far, we're using the qemu64/qemu32 CPU type, which basically
means "the maximum TCG can emulate".
That's a really good default when using TCG, but when running with KVM
we much rather want a default saying "the maximum performance I can get".
Fortunately we just added an option that gives us the best performance
while still staying safe on the testability side of things: -cpu best.
So all we need to do is make -cpu best the default when the user doesn't
explicitly specify a CPU type.
This fixes a lot of subtle breakage in the GNU toolchain (libgmp) which
hicks up on QEMU's non-existent CPU models.
This patch also adds a new pc-1.2 machine type to stay backwards compatible
with older versions of QEMU.
Signed-off-by: Alexander Graf
---
v1 -> v2:
- rebase
v2 -> v3:
- fix typo in commit message
---
hw/pc_piix.c | 34 ++
1 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 0c0096f..a955bf8 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -127,7 +127,8 @@ static void pc_init1(MemoryRegion *system_memory,
const char *initrd_filename,
const char *cpu_model,
int pci_enabled,
- int kvmclock_enabled)
+ int kvmclock_enabled,
+ int may_cpu_best)
{
int i;
ram_addr_t below_4g_mem_size, above_4g_mem_size;
@@ -149,6 +150,9 @@ static void pc_init1(MemoryRegion *system_memory,
MemoryRegion *rom_memory;
void *fw_cfg = NULL;
+if (!cpu_model && kvm_enabled() && may_cpu_best) {
+cpu_model = "best";
+}
pc_cpus_init(cpu_model);
if (kvmclock_enabled) {
@@ -298,7 +302,21 @@ static void pc_init_pci(ram_addr_t ram_size,
get_system_io(),
ram_size, boot_device,
kernel_filename, kernel_cmdline,
- initrd_filename, cpu_model, 1, 1);
+ initrd_filename, cpu_model, 1, 1, 1);
+}
+
+static void pc_init_pci_oldcpu(ram_addr_t ram_size,
+ const char *boot_device,
+ const char *kernel_filename,
+ const char *kernel_cmdline,
+ const char *initrd_filename,
+ const char *cpu_model)
+{
+pc_init1(get_system_memory(),
+ get_system_io(),
+ ram_size, boot_device,
+ kernel_filename, kernel_cmdline,
+ initrd_filename, cpu_model, 1, 1, 0);
}
static void pc_init_pci_no_kvmclock(ram_addr_t ram_size,
@@ -312,7 +330,7 @@ static void pc_init_pci_no_kvmclock(ram_addr_t ram_size,
get_system_io(),
ram_size, boot_device,
kernel_filename, kernel_cmdline,
- initrd_filename, cpu_model, 1, 0);
+ initrd_filename, cpu_model, 1, 0, 0);
}
static void pc_init_isa(ram_addr_t ram_size,
@@ -328,7 +346,7 @@ static void pc_init_isa(ram_addr_t ram_size,
get_system_io(),
ram_size, boot_device,
kernel_filename, kernel_cmdline,
- initrd_filename, cpu_model, 0, 1);
+ initrd_filename, cpu_model, 0, 1, 0);
}
#ifdef CONFIG_XEN
@@ -380,7 +398,7 @@ static QEMUMachine pc_machine_v1_2 = {
static QEMUMachine pc_machine_v1_1 = {
.name = "pc-1.1",
.desc = "Standard PC",
-.init = pc_init_pci,
+.init = pc_init_pci_oldcpu,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
PC_COMPAT_1_1,
@@ -415,7 +433,7 @@ static QEMUMachine pc_machine_v1_1 = {
static QEMUMachine pc_machine_v1_0 = {
.name = "pc-1.0",
.desc = "Standard PC",
-.init = pc_init_pci,
+.init = pc_init_pci_oldcpu,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
PC_COMPAT_1_0,
@@ -430,7 +448,7 @@ static QEMUMachine pc_machine_v1_0 = {
static QEMUMachine pc_machine_v0_15 = {
.name = "pc-0.15",
.desc = "Standard PC",
-.init = pc_init_pci,
+.init = pc_init_pci_oldcpu,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
PC_COMPAT_0_15,
@@ -462,7 +480,7 @@ static QEMUMachine pc_machine_v0_15 = {
static QEMUMachine pc_machine_v0_14 = {
.name = "pc-0.14",
.desc = "Standard PC",
-.init = pc_init_pci,
+.init = pc_init_pci_oldcpu,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
PC_COMPAT_0_14,
--
1.6.0.2
