On 20 November 2013 17:28, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > Il 20/11/2013 00:56, Jim MacArthur ha scritto: >> The question is, how does a new vcpu start up? Will it start in full >> 64-bit mode or 16-bit real mode? > > By default it start in 16-bit real mode, with CS=0xf000 and EIP=0xfff0, > but CS.base = 0xffff0000. However, you can send ioctls to modify > CR0/CR4/EFER and place the VCPU in whatever mode you'd like to have. After reading this I added a call to KVM_GET_SREGS. Everything you say here matches my experience except that CS.base=0xf0000. So I adjusted my memory to cover physical address 0xFFFF0, and now it's happily running instructions (NOPs, at least.) I'm a bit puzzled that it didn't start with CS.base=0xffff0000, but it doesn't matter, I've done what I wanted to do for now. Thanks very much for your help. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
