On 03/25/2010 10:23 PM, Pekka Enberg wrote:
Hi Avi,
Avi Kivity wrote:
When you come up against something that is undocumented or badly
described, please complain on kvm@. We will then update the
documentation.
So one thing I'm wondering is in what mode do we enter the guest? Is
that entirely specified with KVM_SET_REGS and KVM_SET_SREGS?
Yes. cr0.pe = real/protected, eflags.vm = vm86 mode, cs.d =
prot16/prot32, efer.lme/efer.lma/cs.l = longmode.
I assume we're entering real mode as per how I set up "rflags" but for
some reason I'm seeing "cs" base being zeroed out before first
instruction is executed with my simple kvm program which could mean
that it's trying to use GDT (which is not set up at that point).
I see you set up the cpu as if after reset (cs:ip = f000:fff0) but just
dumped a kernel there. That won't work, you need real code.
Try poking 'e9 fd ff' at your entry point (ffff0) and see the cpu pegged
at 100% (1: jmp 1b) (this is probably the largest possible kernel that
is bug-free).
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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