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Bug #637

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Sandybridge: C-States and Turbo not working in coreboot

Bug #637: Sandybridge: C-States and Turbo not working in coreboot

Added by Patrick Rudolph about 4 hours ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
chipset configuration
Target version:
Start date:
04/06/2026
Due date:
% Done:

0%

Estimated time:
Affected versions:
Needs backport to:
Affected hardware:
Affected OS:

Description

Observations showed that in coreboot:

  • C-States are not working (asm("mwait"); has no effect)
  • Turbo states (core above P0 frequency) aren't working

The P-state can be changed after BIOS_RESET_CPL, but it never goes into turbo mode.

On Linux both are working fine.

It would be nice to have both fixed as turbo states could reduce boot time when extracting the LZMA payload.
Tests show that around 20msec of boottime improvements are possible, just for extracting the LZMA payload.

Tested version: 654f32847428f36c92c19932bdfec9f3510bf384

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