** Description changed:
[Impact]
On ARM64 systems enabling cppccontrol=1 in firmware, the dmesg fills with
messages like:
[ 4083.960332] ACPI CPPC: PCC check channel failed. Status=0
[ 4085.546975] ACPI CPPC: PCC check channel failed. Status=0
[ 4113.939921] ACPI CPPC: PCC check channel failed. Status=0
[ 4115.531777] ACPI CPPC: PCC check channel failed. Status=0
We lose any useful data in dmesg and on the console.
[Fix]
upstream commit fixes this issue:
commit 3d41386d556db9f720e00de3e11e45f39cb5071c
Author: George Cherian <[email protected]>
Date: Fri Mar 23 03:30:31 2018 -0700
cpufreq: CPPC: Use transition_delay_us depending transition_latency
[Testing]
-- before kernel patch --
Both console output and dmesg are filled with the message
ACPI CPPC: PCC check channel failed. Status=0
[ 85.969952] ACPI CPPC: PCC check channel failed. Status=0
[ 81.888445] cloud-init[4810]: Cloud-init v. 18.2 running 'modules:final'
at Fri, 13 Apr 2018 19:11:57 +0000. Up 80.71 seconds.
[ 81.888625] cloud-init[4810]: Cloud-init v. 18.2 finished at Fri, 13 Apr
2018 19:11:58 +0000. Datasource DataSourceMAAS
[http://10.228.68.5:5240/MAAS/metadata/]. Up 81.69 seconds
[ OK ] Started Execute cloud user/final scripts.
[ OK ] Reached target Cloud-init target.
[ 86.230432] ACPI CPPC: PCC check channel failed. Status=0
[ 86.701943] ACPI CPPC: PCC check channel failed. Status=0
[ 86.773668] ACPI CPPC: PCC check channel failed. Status=0
[ 87.369958] ACPI CPPC: PCC check channel failed. Status=0
[ 87.733361] ACPI CPPC: PCC check channel failed. Status=0
[ 88.207372] ACPI CPPC: PCC check channel failed. Status=0
- ubuntu@starbuck:~$ uname -a
+ ubuntu@starbuck:~$ uname -a
Linux starbuck 4.15.0-13-generic #14-Ubuntu SMP Sat Mar 17 13:44:36 UTC 2018
aarch64 aarch64 aarch64 GNU/Linux
-- after kernel patch --
+ OK ] Started Apply the settings specified in cloud-config.
+ Starting Execute cloud user/final scripts...
+ [ 67.178425] cloud-init[3688]: Cloud-init v. 18.2 running 'modules:final'
at Fri, 13 Apr 2018 20:41:15 +0000. Up 65.98 seconds.
+ [ 67.200190] cloud-init[3688]: Cloud-init v. 18.2 finished at Fri, 13 Apr
2018 20:41:15 +0000. Datasource DataSourceMAAS
[http://10.228.68.5:5240/MAAS/metadata/]. Up 66.83 seconds
+ [ OK ] Started Execute cloud user/final scripts.
+ [ OK ] Reached target Cloud-init target.
+
+ Ubuntu Bionic Beaver (development branch) starbuck ttyAMA0
+
+ starbuck login:
+
+ ubuntu@starbuck:~$ uname -a
+ Linux starbuck 4.15.0-15-generic #16~lp1763817+build.1 SMP Fri Apr 13
19:54:10 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux
+
+ [Regression Potential]
+ None.
** Changed in: linux (Ubuntu)
Assignee: Canonical Kernel Team (canonical-kernel-team) => Manoj Iyer
(manjo)
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https://bugs.launchpad.net/bugs/1763817
Title:
[SRU][BIONIC] after enabling cppc dmesg fills with "ACPI CPPC: PCC
check channel failed. Status=0"
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