On 10/11/2011 12:04 AM, Borislav Petkov wrote: > Hi Tejun, > > On Mon, Oct 10, 2011 at 02:08:48PM -0400, tj@xxxxxxxxxx wrote: >> Maybe I'm confused but is that patch correct for actual CPU hotplug >> case? If not, what's the point in doing that? What are we gonna do >> after six month some people come up with "CPU hotplug fails to load >> new microcode for the new CPU"? > [...] > >> If somebody is sure that microcode don't need to be changed once >> loaded, then all's good and dandy but that's not the case here, right? > > Well, basically the current situation didn't change the ucode - it > simply reloaded the same image from before going offline. > > See, there's this another problem with what we have right now: imagine > you've just updated the ucode image on disk and offline only a subset of > the cores. Then you online them again and they now get the newer ucode > image while the others still run the old ucode. This could explode or > could not, one thing's for sure: all bets are off. If we don't reload it > on hotplug, we're fine - only module reload triggers the ucode update in > a fairly synchronized manner. > This one makes a lot of sense to me. I hadn't thought of it before. >> If you want to optimize away microcode unloading during >> suspend/resume, the RTTD is doing revalidation / reload during >> CPU_ONLINE as necessary. > > see above. > >> If this use case doesn't really matter too much to anyone, just >> leaving it alone would be better than adding band aid which can lead >> to very obscure issues down the road (oooh, that microcode shouldn't >> have been loaded to that cpu). > > I'd like to actually hear someone justify such a requirement. > > I hope I'm making some sense here. > -- Regards, Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> Linux Technology Center, IBM India Systems and Technology Lab -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
