On Mon, 2008-03-31 at 13:19 -0500, Jerone Young wrote: > On Mon, 2008-03-31 at 13:05 -0500, Josh Boyer wrote: > > On Mon, 31 Mar 2008 12:07:17 -0500 > > Josh Boyer <[EMAIL PROTECTED]> wrote: > > > > > On Mon, 2008-03-31 at 08:12 -0500, Jerone Young wrote: > > > > # HG changeset patch > > > > # User Jerone Young <[EMAIL PROTECTED]> > > > > # Date 1206969060 18000 > > > > # Node ID 10aea37177130bbe5de7bee6ec06d9010bc5da1f > > > > # Parent 1506aa38ddabb0bf73fff3ac3f3db5f9ef6458cc > > > > Add idle power save for ppc 4xx > > > > > > > > This patch sets the wait state MSR when power_save is called in > > > > cpu_idle loop for ppc4xx. This is mainly to help out virtualization > > > > solutions such as KVM. This way the virtualization soultions are able > > > > to tell if the guest kernel is idle. > > > > > > > > I have tested this on hardware & KVM virtual guest. > > > > > > I'm not overly thrilled with adding this to all of 4xx. It doesn't > > > actually save much power at all (1% on a project that actually measured > > > it with an amp meter recently) and there's really no other benefit to > > > doing it outside of the virtual guest case. > > > > > > I'm assuming you pass a dtb to the virtual guest when you start it up. > > > Could you define a property in the CPU node there that can be parsed to > > > use the power_save function instead of always making it the default? > > > > Actually, you probably don't want this as a property in the device > > tree. It doesn't describe hardware. A Kconfig option might be > > warranted though. > > I'll go with the Kconfig option.
Go with a device-tree check. The pseries kernel supports both bare-metal and hypervisor in the same kernel image, and it works out which it's running on by looking at the device-tree. This seems equivalent to me? cheers -- Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person
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