Re: [PATCH 24/26] KVM: PPC: PV mtmsrd L=0 and mtmsr

quoted

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There is also a form of mtmsr where all bits need to be addressed. While the
PPC64 Linux kernel behaves resonably well here, the PPC32 one never uses the
L=1 form but does mtmsr even for simple things like only changing EE.

You make it sound like the 32-bit kernel does something stupid, while
there is no other choice.  The "L=1" thing only exists for 64-bit.

Oh, so that's why :). That doesn't really change the fact that it's very hard to distinguish between a mtmsr that only changes MSR_EE vs one that changes MSR_IR for example :).

Hard to predict for the CPU as well, guess why there is a separate
instruction now :-P

By the way, L=1 _does_ exist for mtmsr; it's just that no 32-bit "classic"
implementations support it.


Segher