[Qemu-devel] [PATCH v2 0/3] target-i386: Don't trigger CPUID warnings by default in KVM mode (in most hosts)

[Eduardo Habkost]

The x86 change to make "check" mode be enabled by default made QEMU print
warnings in the default case if running in an Intel host:

  $ qemu-system-x86_64 -machine pc,accel=kvm
  warning: host doesn't support requested feature: CPUID.80000001H:ECX.sse4a 
[bit 6]

There's also a warning when about missing the ABM feature if running on a Sandy
Bridge or older host.

ABM is not available on Sandy Bridge and older, SSE4a is not available in any
Intel host. We want to make the default CPU runnable in most hosts, so those
features won't be enabled by default in KVM mode.

We should eventually have all features supported by TCG enabled by default in
TCG mode, but as we don't have a good mechanism today to ensure we have
different defaults in KVM and TCG mode, disable ABM and SSE4a in the qemu64 CPU
model entirely.

Also, as we can't change the guest ABI in pc-*-2.4, disable "check" mode by
default in pc-*-2.4 and older so we don't print spurious warnings.

Note that with this change, the qemu64 CPU model still requires a host
supporting POPCNT (Nehalem or newer, and Opteron_G3 or newer).

Eduardo Habkost (3):
  target-i386: Set "check=off" by default on pc-*-2.4 and older
  target-i386: Remove SSE4a from qemu64 CPU model
  target-i386: Remove ABM from qemu64 CPU model

 include/hw/i386/pc.h | 15 +++++++++++++++
 target-i386/cpu.c    |  3 +--
 2 files changed, 16 insertions(+), 2 deletions(-)

-- 
2.1.0