On 25.07.2019 15:47, Roger Pau Monné wrote: > On Thu, Jul 25, 2019 at 09:29:01AM -0400, Fredy P. wrote: >> On Thu, 2019-07-25 at 15:13 +0200, Roger Pau Monné wrote: >>> On Thu, Jul 25, 2019 at 12:54:46PM +0000, Jan Beulich wrote: >>>> On 25.07.2019 14:44, Fredy P. wrote: >>>>> On Wed, 2019-07-24 at 17:41 +0200, Roger Pau Monné wrote: >>>>>>>> What hardware interface does thermald (or the driver in >>>>>>>> Linux if >>>>>>>> there's one) use to get the temperature data? >>>>> >>>>> In our initial POC using Xen 4.8.x we where using Linux coretemp >>>>> driver >>>>> reading by example /class/sys/hwmon/hwmon0/temp3_input but it got >>>>> deprecated at commit 72e038450d3d5de1a39f0cfa2d2b0f9b3d43c6c6 >>>> >>>> Hmm, I wouldn't call this deprecation, but a regression. I would >>>> say we want to re-expose this leaf to Dom0, the more that the >>>> commit also only mentions unprivileged domains. Andrew? >>> >>> AFAICT from the documents provided by Fredy the temperature is read >>> from a MSR that reports the current temperature of the core on which >>> the MSR is read from. When running on Xen this will only work >>> correctly if dom0 is given the same vCPUs as pCPUs and those are >>> identity pinned. >> >> I just want to be sure I got it correctly, by saying "When running on >> Xen this will only work correctly if ..." means in a future >> implementation or that right now could work if I pin this v/pCPUS? > > No, right now there's no way to get this data from dom0, regardless of > the pinning.
Of course you can, using the MSR "device" Linux optionally provides (plus perhaps the rdmsr utility from the msr-tools package). > The commit you mention simply removes exposing the feature on CPUID, > but I'm not sure whether access to the actual MSR is also forbidden. I > think so since we do MSR white listing IIRC, and I don't seem to find > MSR_IA32_THERM_STATUS white listed anywhere. At least for PV we continue to let everything not specially handled shine through - see the bottom of pv/emul-pro-op.c:read_msr(). Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
