Re: [67/90] intel idle: Make idle driver more robust

[Michael Tokarev]

26.01.2012 18:45, Kirill A. Shutemov wrote:

> > From: Thomas Renninger<trenn@xxxxxxx>
> >
> > commit 5c2a9f06a9cd7194f884cdc88144866235dec07d upstream.
> >
> > kvm -cpu host passes the original cpuid info to the guest.
> >
> > Latest kvm version seem to return true for mwait_leaf cpuid
> > function on recent Intel CPUs. But it does not return mwait
> > C-states (mwait_substates), instead zero is returned.
[]
> >   drivers/idle/intel_idle.c |    3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > --- a/drivers/idle/intel_idle.c
> > +++ b/drivers/idle/intel_idle.c
> > @@ -321,7 +321,8 @@ static int intel_idle_probe(void)
> >   	cpuid(CPUID_MWAIT_LEAF,&eax,&ebx,&ecx,&mwait_substates);
> >
> >   	if (!(ecx&  CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
> > -		!(ecx&  CPUID5_ECX_INTERRUPT_BREAK))
> > +	    !(ecx&  CPUID5_ECX_INTERRUPT_BREAK) ||
> > +	    !mwait_substates)
> >   			return -ENODEV;
>
> It breaks build for me.
[]
>    CC      drivers/idle/intel_idle.o
> /home/space/kas/git/public/linux-3.0-mid/drivers/idle/intel_idle.c: In function âintel_idle_probeâ:
> /home/space/kas/git/public/linux-3.0-mid/drivers/idle/intel_idle.c:508:7: error: âmwait_substatesâ undeclared (first use in this function)
> /home/space/kas/git/public/linux-3.0-mid/drivers/idle/intel_idle.c:508:7: note: each undeclared identifier is reported only once for each function it appears in
> make[3]: *** [drivers/idle/intel_idle.o] Error 1
>
> Variable 'substates' hasn't renamed to 'mwait_substates' in 3.0.
> See c423628 intel_idle: delete substates DEBUG modparam

I wonder why in my 3.0.18 this variable is properly defined
in the same file, in line 77:

...
74 /* intel_idle.max_cstate=0 disables driver */
75 static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
76
77 static unsigned int mwait_substates;
78
79 #define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF
...

> Signed-off-by: Kirill A. Shutemov<kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
>   drivers/idle/intel_idle.c |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index 15d72ca..a1aecc3 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -505,7 +505,7 @@ static int intel_idle_probe(void)
>
>   	if (!(ecx&  CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
>   	    !(ecx&  CPUID5_ECX_INTERRUPT_BREAK) ||
> -	    !mwait_substates)
> +	    !substates)

With this patch my build of 3.0.18 fails with "substates undeclared"
message...

>   	if (substates == 0)	/* can over-ride via modparam */

And I don't have this context line in my version.

It is 3.0 from kernel.org patched by patch-3.0.18.xz

Thanks,

/mjt
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