[Libguestfs] [PATCH 2/2] lib: appliance: qemu 2.9.0 supports TCG with -cpu host on x86 (RHBZ#1277744).

Starting with version 2.9.0, qemu can use: qemu-system-x86_64 -M accel=tcg -cpu host without breaking. This only applies to x86 (i386 or x86_64) at the moment. If we detect these conditions, pass -cpu host unconditionally. This should hopefully address problems where other hypervisors (eg. VirtualBox) are running, which breaks KVM in a way that we cannot detect, and consequently breaks libguestfs. --- src/appliance-cpu.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/appliance-cpu.c b/src/appliance-cpu.c index a7cf1eb..fa7e941 100644 --- a/src/appliance-cpu.c +++ b/src/appliance-cpu.c @@ -63,7 +63,7 @@ * * We don't know for sure if KVM will work, but C<-cpu host> is broken * with TCG, so we almost always pass a broken C<-cpu> flag if KVM is - * semi-broken in any way. + * semi-broken in any way. (This is fixed in qemu 2.9, thanks Eduardo!) * * =back */ @@ -77,6 +77,14 @@ guestfs_int_get_cpu_model (int kvm, const struct version *qemu_version) else return "cortex-a57"; #else +#if defined(__i386__) || defined(__x86_64__) + /* Eduardo added the ability to use -cpu host with TCG on x86 in + * qemu 2.9. + */ + if (guestfs_int_version_ge (qemu_version, 2, 9, 0)) + return "host"; + /* otherwise fallthrough */ +#endif /* On most architectures, it is faster to pass the CPU host model to * the appliance, allowing maximum speed for things like checksums * and encryption. Only do this with KVM. It is broken in subtle -- 2.10.2