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Would it be possible for hardware to have a bit set that is >>> not supported? Would that mean it is actually supported or a hardware bug? >> >> No. Hardware supports all the bits reported here. Like i said before >> wanted to remove the hard-coded value. > > The size of the field in the register is different information from what > the value of that field may be. Yes. it could be. > > >> >>> >>>> } >>>> >>>> static void mondata_config_read(struct rdt_domain *d, struct mon_config_info *mon_info) >>>> @@ -1621,7 +1621,7 @@ static int mbm_config_write_domain(struct rdt_resource *r, >>>> int ret = 0; >>>> >>>> /* mon_config cannot be more than the supported set of events */ >>>> - if (val > MAX_EVT_CONFIG_BITS) { >>>> + if (val > resctrl_max_evt_bitmask) { >>>> rdt_last_cmd_puts("Invalid event configuration\n"); >>>> return -EINVAL; >>>> } >>> >>> This does not look right. resctrl_max_evt_bitmask contains the supported >>> types. A user may set a value that is less than resctrl_max_evt_bitmask but >>> yet have an unsupported bit set, no? >> >> I think I have to make this clear in the patch. There is no difference in >> the definition. Hardware supports all the events reported by the cpuid. > > I'll try to elaborate using an example. Let's say AMD decides to make > hardware with hypothetical support mask of: > resctrl_max_evt_bitmask = 0x4F (no support for Slow Mem). > > What if user attempts to set config that enables monitoring of Slow Mem: > val = 0x30 > > In the above example, val is not larger than resctrl_max_evt_bitmask > but it is an invalid config, no? Yes. It is invalid config in this case. How about changing the check to something like this? if ((val & resctrl_max_evt_bitmask) != val) { rdt_last_cmd_puts("Invalid event configuration\n"); return -EINVAL; } -- Thanks Babu Moger