[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] cpufreq support status
>From: Jan Beulich >Sent: 2007年10月24日 16:28 > >Looking into this some more, I find that >ACPI_ADR_SPACE_FIXED_HARDWARE >is mostly unsupported in Linux except for C-state handling, in which case >is >resolves to MWAIT. > FFH is mapped to msr for P-state handling on Intel processors. You can refer to acpi-cpufreq.c in latest native Linux kernel, where have logic to handle both IO space and FFH space. Since 2.6.2*, acpi-cpufreq.c is the preferred cpufreq driver for intel processors. But if you look at the current 2.6.18-xen, acpi-cpufreq.c can only handle I/O space and instead speedstep-centrino.c manipulates FFH, i.e. MSR directly. But because the _PDC capabilities is set to FFH capable in 2.6.18, speedstep_centrino.c becomes the only drive working in this environment then. Thanks, Kevin _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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