========================= x86-specific random items ========================= Userspace poking at MSRs ------------------------- The kernel may dump a warning message of the format "msr: Write to unrecognized MSR $MSR_ADDR by $COMM" where MSR_ADDR and COMM are documented in the table below. This warning message does not affect the system in any way - it is only there to gather info which userspace tools are poking at model-specific registers (MSRs) with the intent to fix them because userspace should not access MSRs - that's the kernel's job. Info below has been gathered so far by the kind help of reporters (big thanks!). If you find a MSR reported on your system, in the table below, the text under it should tell you what to do. If not, please report it to x86@kernel.org. Thx. MSR_ADDR COMM =============================================================================== 0x38f (PERF_GLOBAL_CTRL) i7z 0x38d (PERF_FIXED_CTR_CTRL) No userspace tool should touch those. Tool needs fixing, Authors pinged. ------------------------------------------------------------------------------- 0x150 (MSR_OC_MAILBOX) throttled 0x1a2 (MSR_IA32_TEMPERATURE_TARGET) intel-undervolt 0x610 (MSR_PKG_POWER_LIMIT) Work ongoing towards converting to sysfs interfaces. ------------------------------------------------------------------------------- 0x49 perl (spectre-meltdown-checker.sh) 0x10b perl, older x86_energy_perf $ grep -r . /sys/devices/system/cpu/vulnerabilities/ should give all the information needed to know which CPU vulnerabilities have been applied. This script is not needed. When x86_energy_perf causes this warning, then it is most likely caused by using an old tool supplied by the distro, with a newer kernel. Versions of the tool carved out from the 5.11 kernel are fixed. ------------------------------------------------------------------------------- 0xc0010015 python (ZenStates) 0xc0010292 Supposed to fix some freezes on Zen machines but no definitive proof yet. ------------------------------------------------------------------------------- 0x17f mcelog Fix is in v5.11: 68299a42f842 ("x86/mce: Enable additional error logging on certain Intel CPUs") ------------------------------------------------------------------------------- 0xc0010067 k10ctl Some AMD F10h undervolting, should simply use cpufreq governor. Not needed. ------------------------------------------------------------------------------- 0x1a4 (MSR_MISC_FEATURE_CONTROL) xmrig Reportedly disabling hardware prefetchers improves performance for some miners on some CPUs: https://github.com/xmrig/xmrig/issues/1433#issuecomment-572126184 after pointing at: https://software.intel.com/content/www/us/en/develop/articles/disclosure-of-hw-prefetcher-control-on-some-intel-processors.html The kernel's resctrl code touches that MSR too so if anything, this needs a proper kernel interface to sync accesses to those MSRs and the hw pref control. Also, those bits are different per model so it needs model logic too --------------------------------------------------------------------------------