When turbo mode is unavailable on a Skylake-X system, executing the
command:
"echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo"
results in an unchecked MSR access error: WRMSR to 0x199
(attempted to write 0x0000000100001300).
This issue was reproduced on an OEM (Original Equipment Manufacturer)
system and is not a common problem across all Skylake-X systems.
This error occurs because the MSR 0x199 Turbo Engage Bit (bit 32) is set
when turbo mode is disabled. The issue arises when intel_pstate fails to
detect that turbo mode is disabled. Here intel_pstate relies on
MSR_IA32_MISC_ENABLE bit 38 to determine the status of turbo mode.
However, on this system, bit 38 is not set even when turbo mode is
disabled.
According to the Intel Software Developer's Manual (SDM), the BIOS sets
this bit during platform initialization to enable or disable
opportunistic processor performance operations. Logically, this bit
should be set in such cases. However, the SDM also specifies that "OS and
applications must use CPUID leaf 06H to detect processors with
opportunistic processor performance operations enabled."
Therefore, in addition to checking MSR_IA32_MISC_ENABLE bit 38, verify
that CPUID.06H:EAX[1] is 0 to accurately determine if turbo mode is
disabled.
Fixes: 4521e1a0ce17 ("cpufreq: intel_pstate: Reflect current no_turbo state correctly")
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada(a)linux.intel.com>
Cc: stable(a)vger.kernel.org
---
drivers/cpufreq/intel_pstate.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index f41ed0b9e610..ba9bf06f1c77 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -598,6 +598,9 @@ static bool turbo_is_disabled(void)
{
u64 misc_en;
+ if (!cpu_feature_enabled(X86_FEATURE_IDA))
+ return true;
+
rdmsrl(MSR_IA32_MISC_ENABLE, misc_en);
return !!(misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
--
2.48.1
For some odd reason 5.10 kernel series doesn't compile with a newer
toolchain since 2025-02-09:
2025-02-09T17:32:07.7991299Z GEN .version
2025-02-09T17:32:07.8270062Z CHK include/generated/compile.h
2025-02-09T17:32:07.8540777Z LD vmlinux.o
2025-02-09T17:32:11.7210899Z MODPOST vmlinux.symvers
2025-02-09T17:32:12.0869599Z MODINFO modules.builtin.modinfo
2025-02-09T17:32:12.1403022Z GEN modules.builtin
2025-02-09T17:32:12.1475659Z LD .tmp_vmlinux.btf
2025-02-09T17:32:19.6117204Z BTF .btf.vmlinux.bin.o
2025-02-09T17:32:31.2916650Z LD .tmp_vmlinux.kallsyms1
2025-02-09T17:32:34.8731104Z KSYMS .tmp_vmlinux.kallsyms1.S
2025-02-09T17:32:35.4910608Z AS .tmp_vmlinux.kallsyms1.o
2025-02-09T17:32:35.9662538Z LD .tmp_vmlinux.kallsyms2
2025-02-09T17:32:39.2595984Z KSYMS .tmp_vmlinux.kallsyms2.S
2025-02-09T17:32:39.8802028Z AS .tmp_vmlinux.kallsyms2.o
2025-02-09T17:32:40.3659440Z LD vmlinux
2025-02-09T17:32:48.0031558Z BTFIDS vmlinux
2025-02-09T17:32:48.0143553Z FAILED unresolved symbol filp_close
2025-02-09T17:32:48.5019928Z make: *** [Makefile:1207: vmlinux] Error 255
2025-02-09T17:32:48.5061241Z ==> ERROR: A failure occurred in build().
5.10.234 built fine couple of days ago with the older one. There were
slight changes made. 5.4 and 5.15 still compile.
Wonder what might be missing here ...
--
Best, Philip
Dear Kernel maintainers,
I think i'm encountering (for the first time in years !) a regression
with the "6.7.arch3-1" kernel (whereas no issues with
"6.6.10.arch1-1", on which i reverted).
I'm running a (up-to-date, and non-LTS) ARCHLINUX desktop, on a ASUS
B560-I motherboard, with 3 monitors (attached to a 4-HDMI outputs
card), plus an audio S/PDIF optic output at motherboard level.
With the latest kernel, the S/PIDF optic output of the motherboard is
NOT detected anymore (and i haven't been able to see / find anything
in the logs at quick glance, neither journalctl -xe nor dmesg).
Once reverted to 6.6.10, everything is fine again.
For example, in a working situation (6.6.10), i have :
cat /proc/asound/pcm
00-00: ALC1220 Analog : ALC1220 Analog : playback 1 : capture 1
00-01: ALC1220 Digital : ALC1220 Digital : playback 1
00-02: ALC1220 Alt Analog : ALC1220 Alt Analog : capture 1
01-03: HDMI 0 : HDMI 0 : playback 1
01-07: HDMI 1 : HDMI 1 : playback 1
01-08: HDMI 2 : HDMI 2 : playback 1
01-09: HDMI 3 : HDMI 3 : playback 1
Whereas while on the latest 6.7 kernel, i only had the 4 HDMI lines
(linked to a NVIDIA T600 card, with 4 HDMI outputs) and not the three
first ones (attached to the motherboard).
(of course i did several tests with 6.7, reboot, ... without any changes)
Any idea ?
Best regards
--
Serge.