On 16.02.2012, at 17:58, Scott Wood wrote: > On 02/16/2012 04:24 AM, Alexander Graf wrote: >> On 16.02.2012, at 10:26, Liu Yu <yu.liu@xxxxxxxxxxxxx> wrote: >>> +_GLOBAL(epapr_ev_idle) >>> +epapr_ev_idle: >>> + rlwinm r3,r1,0,0,31-THREAD_SHIFT /* current thread_info */ >>> + lwz r4,TI_LOCAL_FLAGS(r3) /* set napping bit */ >>> + ori r4,r4,_TLF_NAPPING /* so when we take an exception */ >>> + stw r4,TI_LOCAL_FLAGS(r3) /* it will return to our caller */ >>> + >>> + wrteei 1 >>> + >>> +idle_loop: >>> + LOAD_REG_IMMEDIATE(r11, HC_VENDOR_EPAPR | HC_EV_IDLE) >>> + >>> +.global epapr_ev_idle_start >>> +epapr_ev_idle_start: >>> + li r3, -1 >>> + nop >>> + nop >>> + nop >> >> Can't you just bl into epapr_hypercall_start? You don't even have to save the old lr. because we never return anyways :) > > The interrupt will branch to LR, so no, we can't trash it or put it > anywhere else. 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? Then we don't have to replicate the hypercall code all over again for every invocation. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
