On 16.02.2012, at 18:36, Scott Wood wrote: > On 02/16/2012 11:30 AM, Alexander Graf wrote: >> >> On 16.02.2012, at 18:28, Scott Wood wrote: >> >>> On 02/16/2012 11:18 AM, Alexander Graf wrote: >>>> Hrm. But we can clobber ctr, right? So how about we make the generic version do a bctr and then just do a small C wrapper that takes lr, moves it to ctr and branches to the generic one? >>> >>> If it's just for this, I would say don't mess with the normal hcall path >>> for the sake of idle. If using CTR would let us get away without >>> creating a stack frame in call sites, maybe that would be worthwhile, >>> depending on what sort of hcalls we end up having. >>> >>>> Then we don't have to replicate the hypercall code all over again for every invocation. >>> >>> We shouldn't need to do it for every invocation. Idle is special due to >>> the TLF_NAPPING hack. >> >> Famous last words. If it's the only case, duplication should be ok. Let's hope there are no others. > > Actually, we can't use CTR -- it's volatile in the ePAPR hypercall ABI. Ugh. Alrighty, let's duplicate the hc code then. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
