Re: [Qemu-devel] [PATCH v2] hw/isa/lpc_ich9: inject SMI on all VCPUs if APM_STS == 'Q'

[Paolo Bonzini]

On 16/11/2016 14:18, Michael S. Tsirkin wrote:
> > - we could have another magic 0xB2 value, which is implemented directly
> > in QEMU and sets 0xB3 to a magic value.  Then OVMF can invoke it
> > after SMBASE relocation and SMM IPL (so as not to crash on old QEMUs)
> > to detect the new feature.  It can fail to start if using traditional
> > AP and the new feature is not there.
> 
> If we keep collecting these magic values, should architect it
> and do a host/guest bitmap like virtio does?

The value written in 0xB3 can certainly be a feature bitmap.  For now we
would have for example

bit 0   if set, writing 0x10-0xFF to 0xB2 results in a broadcast SMI
bit 1-7 zero

Paolo