fwts: C state capability support check fails
Bug #833644 reported by
Alex Hung
This bug affects 1 person
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
fwts (Ubuntu) |
Fix Released
|
Low
|
Colin Ian King |
Bug Description
Ubuntu Version: 11.04
FWTS version: 0.22.14
Expected:
FWTS should report that C2/C3 are supported.
Instead:
FWTS reports C2/C3 are not supported as it checks P_LVL2_LAT and P_LVL3_LAT. C states can be also supported by _CST objects.
Changed in fwts (Ubuntu): | |
status: | New → In Progress |
importance: | Undecided → Medium |
assignee: | nobody → Colin King (colin-king) |
summary: |
- C state capability support check fails + fwts: C state capability support check fails |
Changed in fwts (Ubuntu): | |
status: | In Progress → Fix Released |
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@Alex,
So I've scanned a bunch of machines and some have P_LVL2_LAT and P_LVL3_LAT defined as non supporting C2/C3 and the DSDT does not contain a _CST. Some newer CPUs such a Sandybridge are configured like this and the Intel idle driver figures out the number of C states from the CPU id rather than trusting the firmware provided data (be it existent or not).
So.. perhaps I could phrase the warning something like:
"FADT P_LVL2_LAT is 101, a value > 100 indicates that the C2 state is not defined in the FADT. C states either defined in the _CST object or determined by the kernel from the CPU id."