Re: [Xen-ia64-devel][Patch]Add two PAL calls which fix SMPwindowsinstallation crashing bug

[Kouya SHIMURA <kouya@xxxxxxxxxxxxxx>]

Tristan Gingold writes:
 > > In 10, I don't understand why the special SAL_XEN_SAL_RETURN is
 > > necessary instead of PAL_HALT. The difference is test_and_set_bit() or
 > > set_bit(). I think a vcpu with VCPU_down state never be at this point.
 > > Besides calling vcpu_sleep_no_sync() with VCPU_down state seems to be
 > > harmless.
 > Humm, to be discussed:
 > Although the implementation may be almost the same, I think the semantic is
 > not.
 > After SAL_XEN_SAL_RETURN, the processor can be awaken only by a rendez-vous.
 > Its state is reset.
 > 
 > After PAL_HALT, the processor can be awaken by an IPI. Its state is 
 > preserved.
 > 
 > Tristan.

I see. For example, preserving a vcpu context is unnecessary after
SAL_XEN_SAL_RETURN for save/restore of a domain.

Thanks,
Kouya


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