On 07/10/15 16:59, Paolo Bonzini wrote: > > > On 10/07/2015 16:57, Laszlo Ersek wrote: >>>> ... In any case, please understand that I'm not campaigning for this >>>> warning :) IIRC the warning was your (very welcome!) idea after I >>>> reported the problem; I'm just trying to ensure that the warning match >>>> the exact issue I encountered. >>> >>> Yup. I think the right thing to do would be to hide memory above the >>> limit. >> How so? >> >> - The stack would not be doing what the user asks for. Pass -m <a_lot>, >> and the guest would silently see less memory. If the user found out, >> he'd immediately ask (or set out debugging) why. I think if the user's >> request cannot be satisfied, the stack should fail hard. > > That's another possibility. I think both of them are wrong depending on > _why_ you're using "-m <a lot>" in the first place. > > Considering that this really happens (on Xeons) only for 1TB+ guests, I reported this issue because I ran into it with a ~64GB guest. From my /proc/cpuinfo: model name : Intel(R) Core(TM) i7 CPU M 620 @ 2.67GHz address sizes : 36 bits physical, 48 bits virtual I was specifically developing 64GB+ support for OVMF, and this limitation caused me to think that there was a bug in my OVMF patches. (There wasn't.) An error message from QEMU, advising me to turn off EPT, would have saved me many hours. Thanks Laszlo > it's probably just for debugging and then hiding the memory makes some > sense. > > Paolo > -- 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
