* Alexander Graf <agraf@xxxxxxx> [2012-01-08 17:53]:
> 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".
it also means we all maximum possible migration targets. Have you
given any thought to migration with -cpu best?
>
> 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
> define any.
>
> This fixes a lot of subtile breakage in the GNU toolchain (libgmp) which
> hicks up on QEMU's non-existent CPU models.
>
> This patch also adds a new pc-1.1 machine type to keep backwards compatible
> with older versions of QEMU.
>
> Signed-off-by: Alexander Graf <agraf@xxxxxxx>
> ---
> hw/pc_piix.c | 42 ++++++++++++++++++++++++++++++++++--------
> 1 files changed, 34 insertions(+), 8 deletions(-)
>
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 00f525e..3d78ccb 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -79,7 +79,8 @@ 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;
> @@ -102,6 +103,9 @@ static void pc_init1(MemoryRegion *system_memory,
> MemoryRegion *rom_memory;
> DeviceState *dev;
>
> + if (!cpu_model && kvm_enabled() && may_cpu_best) {
> + cpu_model = "best";
> + }
> pc_cpus_init(cpu_model);
>
> if (kvmclock_enabled) {
> @@ -263,7 +267,21 @@ 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,
> @@ -277,7 +295,7 @@ 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,
> @@ -293,7 +311,7 @@ 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
> @@ -314,8 +332,8 @@ static void pc_xen_hvm_init(ram_addr_t ram_size,
> }
> #endif
>
> -static QEMUMachine pc_machine_v1_0 = {
> - .name = "pc-1.0",
> +static QEMUMachine pc_machine_v1_1 = {
> + .name = "pc-1.1",
> .alias = "pc",
> .desc = "Standard PC",
> .init = pc_init_pci,
> @@ -323,17 +341,24 @@ static QEMUMachine pc_machine_v1_0 = {
> .is_default = 1,
> };
>
> +static QEMUMachine pc_machine_v1_0 = {
> + .name = "pc-1.0",
> + .desc = "Standard PC",
> + .init = pc_init_pci_oldcpu,
> + .max_cpus = 255,
> +};
> +
> 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,
> };
>
> 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[]) {
> {
> @@ -612,6 +637,7 @@ static QEMUMachine xenfv_machine = {
>
> static void pc_machine_init(void)
> {
> + qemu_register_machine(&pc_machine_v1_1);
> qemu_register_machine(&pc_machine_v1_0);
> qemu_register_machine(&pc_machine_v0_15);
> qemu_register_machine(&pc_machine_v0_14);
> --
> 1.6.0.2
>
--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
ryanh@xxxxxxxxxx
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