RE: [tip:x86/hyperv] X86: Handle Hyper-V vmbus interrupts asspecial hypervisor interrupts

From: KY Srinivasan
Date: Wed Feb 13 2013 - 07:49:09 EST




> -----Original Message-----
> From: yhlu.kernel@xxxxxxxxx [mailto:yhlu.kernel@xxxxxxxxx] On Behalf Of
> Yinghai Lu
> Sent: Tuesday, February 12, 2013 11:43 PM
> To: KY Srinivasan
> Cc: H. Peter Anvin; mingo@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> tglx@xxxxxxxxxxxxx; hpa@xxxxxxxxxxxxxxx; linux-tip-commits@xxxxxxxxxxxxxxx
> Subject: Re: [tip:x86/hyperv] X86: Handle Hyper-V vmbus interrupts as special
> hypervisor interrupts
>
> On Tue, Feb 12, 2013 at 7:58 PM, KY Srinivasan <kys@xxxxxxxxxxxxx> wrote:
> >
> >
> >> -----Original Message-----
> >> From: H. Peter Anvin [mailto:hpa@xxxxxxxxx]
> >> Sent: Tuesday, February 12, 2013 10:55 PM
> >> To: KY Srinivasan
> >> Cc: Yinghai Lu; mingo@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> >> tglx@xxxxxxxxxxxxx; hpa@xxxxxxxxxxxxxxx; linux-tip-commits@xxxxxxxxxxxxxxx
> >> Subject: Re: [tip:x86/hyperv] X86: Handle Hyper-V vmbus interrupts as special
> >> hypervisor interrupts
> >>
> >> On 02/12/2013 07:49 PM, KY Srinivasan wrote:
> >> >>>
> >> >>> The issue was that you could turn on CONFIG_HYPERV without enabling
> >> >>> CONFIG_X86_LOCAL_APIC. Peter fixed it.
> >> >>>
> >> >>
> >> >> He is asking why you are using IS_ENABLED() instead of #ifdef. The
> >> >> difference is that IS_ENABLED() works even for modules.
> >> >
> >> > My mistake!
> >> >
> >>
> >> Well, which one do you need?
> >
> > I chose the IS_ENABLED() because I wanted to cover the case where HYPERV is
> configured as a module as well.
> >
>
> ok, so when HYPERV is built as module, actually it is partially module
> as it put some code built-in already?
> if user never load hyperv, those code will never not be used.
>
> Can those code not be put in module _init function?

Some code in mshyperv.c is built into the kernel. Registering an IDT entry is dependent on HYPERV drivers being configured - either as modules or built-in.

K. Y
>
> Thanks
>
> Yinghai
>


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