BUG Report: "config KVM" selects PREEMPT_NOTIFIERS, but it should also select PREEMPT (Vanilla Kernel 2.6.30)

BUG Report: "config KVM" selects PREEMPT_NOTIFIERS, but it should also select PREEMPT (Vanilla Kernel 2.6.30)

[Walther Maldonado]

Good day,

Today when attempting to compile and install the KVM module (kernel 2.6.30), inserting the module would error with a number of unresolved symbols such as preempt_notifier_register() not found.

Some code-browsing revealed that, even though the kvm KConfig setting "KVM" does select PREEMPT_NOTIFIERS, in include/linux/preempt.h, said define will not cause the expected functions to be defined unless CONFIG_PREEMPT is also selected.

But I don't have CONFIG_PREEMPT (Preemptible Kernel), my kernel was configured with CONFIG_PREEMPT_VOLUNTARY (Voluntary Kernel Preemption). Since the define CONFIG_PREEMPT_NOTIFIERS is used in other files other than preempt.h, the bug might be in KVM's Kconfig file (in my case, arch/x86/kConfig) not selecting/depending on the right config parameters.

Cheers,
Walther

PS: If there is a need to reply, please do so directly as I am not subscribed to the mailing list.

Re: BUG Report: "config KVM" selects PREEMPT_NOTIFIERS, but it should also select PREEMPT (Vanilla Kernel 2.6.30)

[Avi Kivity]

On 06/29/2009 06:18 PM, Walther Maldonado wrote:
> Good day,
>
> Today when attempting to compile and install the KVM module (kernel 2.6.30), inserting the module would error with a number of unresolved symbols such as preempt_notifier_register() not found.
>
> Some code-browsing revealed that, even though the kvm KConfig setting "KVM" does select PREEMPT_NOTIFIERS, in include/linux/preempt.h, said define will not cause the expected functions to be defined unless CONFIG_PREEMPT is also selected.
>
>    

Not in my copy of v2.6.30.  preempt.h only guards the preempt notifier 
symbols with CONFIG_PREEMPT_NOTIFIER.

I built sched.o with CONFIG_PREEMPT_NONE=y and see:

[avi@cleopatra linux-2.6 (v2.6.30)]$ nm kernel/sched.o  | grep 
preempt_notifier
00000000c559bf4c A __crc_preempt_notifier_register
000000008be61cbb A __crc_preempt_notifier_unregister
0000000000000028 r __kcrctab_preempt_notifier_register
0000000000000020 r __kcrctab_preempt_notifier_unregister
0000000000000232 r __kstrtab_preempt_notifier_register
0000000000000216 r __kstrtab_preempt_notifier_unregister
0000000000000050 r __ksymtab_preempt_notifier_register
0000000000000040 r __ksymtab_preempt_notifier_unregister
0000000000000c77 T preempt_notifier_register
0000000000000caf T preempt_notifier_unregister

Perhaps you have a stale kernel installed?  Try reinstalling the kernel 
and modules and rebooting.

-- 
error compiling committee.c: too many arguments to function

Re: BUG Report: "config KVM" selects PREEMPT_NOTIFIERS, but it should also select PREEMPT (Vanilla Kernel 2.6.30)

[Walther Maldonado]

Good day,

Alright, my bad. After closer studying I realized I had misread where the defines were delimiting each function. :/ Sorry for the invalid report (and yes, I had other issues setting up and running the modules, but I was pretty sure the missing symbols were caused because of the define, which turned out to be false).

Cheers~
Walther.

On Wed, 1 Jul 2009 11:41:38 +0200
Avi Kivity <avi@redhat.com> wrote:

> On 06/29/2009 06:18 PM, Walther Maldonado wrote:
> > Good day,
> >
> > Today when attempting to compile and install the KVM module (kernel 2.6.30), inserting the module would error with a number of unresolved symbols such as preempt_notifier_register() not found.
> >
> > Some code-browsing revealed that, even though the kvm KConfig setting "KVM" does select PREEMPT_NOTIFIERS, in include/linux/preempt.h, said define will not cause the expected functions to be defined unless CONFIG_PREEMPT is also selected.
> >
> >    
> 
> Not in my copy of v2.6.30.  preempt.h only guards the preempt notifier 
> symbols with CONFIG_PREEMPT_NOTIFIER.
> 
> I built sched.o with CONFIG_PREEMPT_NONE=y and see:
> 
> [avi@cleopatra linux-2.6 (v2.6.30)]$ nm kernel/sched.o  | grep 
> preempt_notifier
> 00000000c559bf4c A __crc_preempt_notifier_register
> 000000008be61cbb A __crc_preempt_notifier_unregister
> 0000000000000028 r __kcrctab_preempt_notifier_register
> 0000000000000020 r __kcrctab_preempt_notifier_unregister
> 0000000000000232 r __kstrtab_preempt_notifier_register
> 0000000000000216 r __kstrtab_preempt_notifier_unregister
> 0000000000000050 r __ksymtab_preempt_notifier_register
> 0000000000000040 r __ksymtab_preempt_notifier_unregister
> 0000000000000c77 T preempt_notifier_register
> 0000000000000caf T preempt_notifier_unregister
> 
> Perhaps you have a stale kernel installed?  Try reinstalling the kernel 
> and modules and rebooting.
> 
> -- 
> error compiling committee.c: too many arguments to function
>