SPR_SCR_IPI_PEND
scr_mask |= SPR_SCR_IPI_PEND(n);
scr_mask |= SPR_SCR_IPI_PEND(target);
mtspr(SPR_SCR, spr & ~SPR_SCR_IPI_PEND(cpu_num));
} while ((spr & SPR_SCR_IPI_PEND(cpu_num)) != 0);
if ((spr & SPR_SCR_IPI_PEND(cpu_num)) != 0) {