Build failure w/o mmu notifiers

Build failure w/o mmu notifiers

[Alexander Graf]

Hi,

I'm currently experiencing build failures when CONFIG_MMU_NOTIFIERS is  
not set. Is this intended? If so, it might be nice to put a configure- 
check or #error somewhere to tell the user that enabling mmu notifiers  
became mandatory.

Alex

Re: Build failure w/o mmu notifiers

[Sheng Yang]

On Fri, Oct 17, 2008 at 06:34:35PM +0200, Alexander Graf wrote:
> Hi,
>
> I'm currently experiencing build failures when CONFIG_MMU_NOTIFIERS is  
> not set. Is this intended? If so, it might be nice to put a configure- 
> check or #error somewhere to tell the user that enabling mmu notifiers  
> became mandatory.

Yeah, I think it's intended. In fact, it was selected by KVM
, so if you compile a kernel with KVM, I think it would work...

--
regards
Yang, Sheng

>
> Alex
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Build failure w/o mmu notifiers

[Alexander Graf]

On 17.10.2008, at 19:25, Sheng Yang wrote:

> On Fri, Oct 17, 2008 at 06:34:35PM +0200, Alexander Graf wrote:
>> Hi,
>>
>> I'm currently experiencing build failures when CONFIG_MMU_NOTIFIERS  
>> is
>> not set. Is this intended? If so, it might be nice to put a  
>> configure-
>> check or #error somewhere to tell the user that enabling mmu  
>> notifiers
>> became mandatory.
>
> Yeah, I think it's intended. In fact, it was selected by KVM
> , so if you compile a kernel with KVM, I think it would work...

Well - it makes it pretty hard to build KVM as an external module  
(which I prefer due to many reasons) and I've actually had a problem  
to find the option in make menuconfig somewhere - is it even selectable?

Alex

Re: Build failure w/o mmu notifiers

[Sheng Yang]

On Fri, Oct 17, 2008 at 07:47:39PM +0200, Alexander Graf wrote:
>
> On 17.10.2008, at 19:25, Sheng Yang wrote:
>
>> On Fri, Oct 17, 2008 at 06:34:35PM +0200, Alexander Graf wrote:
>>> Hi,
>>>
>>> I'm currently experiencing build failures when CONFIG_MMU_NOTIFIERS  
>>> is
>>> not set. Is this intended? If so, it might be nice to put a  
>>> configure-
>>> check or #error somewhere to tell the user that enabling mmu  
>>> notifiers
>>> became mandatory.
>>
>> Yeah, I think it's intended. In fact, it was selected by KVM
>> , so if you compile a kernel with KVM, I think it would work...
>
> Well - it makes it pretty hard to build KVM as an external module (which 
> I prefer due to many reasons) and I've actually had a problem to find the 
> option in make menuconfig somewhere - is it even selectable?

CONFIG_MMU_NOITFIER? No... It's automatically selected, if you select KVM,
either in-kernel or module. Please refer to arch/x86/kvm/Kconfig.
--
regards
Yang, Sheng
>
> Alex
>

Re: Build failure w/o mmu notifiers

[Alexander Graf]

Am 17.10.2008 um 20:17 schrieb Sheng Yang <yasker@gmail.com>:

> On Fri, Oct 17, 2008 at 07:47:39PM +0200, Alexander Graf wrote:
>>
>> On 17.10.2008, at 19:25, Sheng Yang wrote:
>>
>>> On Fri, Oct 17, 2008 at 06:34:35PM +0200, Alexander Graf wrote:
>>>> Hi,
>>>>
>>>> I'm currently experiencing build failures when CONFIG_MMU_NOTIFIERS
>>>> is
>>>> not set. Is this intended? If so, it might be nice to put a
>>>> configure-
>>>> check or #error somewhere to tell the user that enabling mmu
>>>> notifiers
>>>> became mandatory.
>>>
>>> Yeah, I think it's intended. In fact, it was selected by KVM
>>> , so if you compile a kernel with KVM, I think it would work...
>>
>> Well - it makes it pretty hard to build KVM as an external module  
>> (which
>> I prefer due to many reasons) and I've actually had a problem to  
>> find the
>> option in make menuconfig somewhere - is it even selectable?
>
> CONFIG_MMU_NOITFIER? No... It's automatically selected, if you  
> select KVM,
> either in-kernel or module. Please refer to arch/x86/kvm/Kconfig.

So if I don't select kvm in the kernel (either as module or compiled  
in) I can't build an external module providing kvm's functionality?  
That doesn't seem really useful to me...

Alex

>
> --
> regards
> Yang, Sheng
>>
>> Alex
>>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Build failure w/o mmu notifiers

[Andrea Arcangeli]

Hi Alexander,

On Fri, Oct 17, 2008 at 08:36:08PM +0200, Alexander Graf wrote:
> So if I don't select kvm in the kernel (either as module or compiled in) I 
> can't build an external module providing kvm's functionality? That doesn't 
> seem really useful to me...

The external module is supposed to still build against older kernels
that don't have mmu notifier functionality at all regardless of their
build config. So it should build on latest kernel with kvm disabled
too (as mentioned here, MMU_NOTIFIER isn't explicitly selectable, it
gets set implicitly if kvm is selected), if it doesn't it's probably
some glitch that needs fixing. Or perhaps if it's not a vanilla kernel
you're building against and a third party patch interfering, just
wondering. I'll try to reproduce with vanilla mainline to see if
something broke, in any case you can post the build failure if the
problem persists.

Thanks!
Andrea

Re: Build failure w/o mmu notifiers

[Avi Kivity]

Alexander Graf wrote:
>
> So if I don't select kvm in the kernel (either as module or compiled 
> in) I can't build an external module providing kvm's functionality? 
> That doesn't seem really useful to me...
>

The external module hackball should detect that you don't have 
CONFIG_MMU_NOTIFIERS set and supply some compatibility glue.  What error 
are you seeing?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

Re: Build failure w/o mmu notifiers

[Alexander Graf]

On 18.10.2008, at 12:51, Avi Kivity wrote:

> Alexander Graf wrote:
>>
>> So if I don't select kvm in the kernel (either as module or  
>> compiled in) I can't build an external module providing kvm's  
>> functionality? That doesn't seem really useful to me...
>>
>
> The external module hackball should detect that you don't have  
> CONFIG_MMU_NOTIFIERS set and supply some compatibility glue.  What  
> error are you seeing?

Basically struct mmu_notifier is not found, but requested by the code:

rm -f include/asm include-compat/asm
ln -sf asm-x86 include/asm
ln -sf asm-x86 include-compat/asm
make -C /usr/src/linux-obj/i586/default M=`pwd` \
		LINUXINCLUDE="-I`pwd`/include -Iinclude \
		-Iinclude2 -I/lib/modules/2.6.27.1-2-default/source/include \
		-Iarch/x86/include -I`pwd`/include-compat \
		-include include/linux/autoconf.h \
		-include `pwd`/x86/external-module-compat.h "
make[1]: Entering directory `/usr/src/linux-2.6.27.1-2-obj/i386/default'
make -C ../../../linux-2.6.27.1-2 O=/usr/src/linux-2.6.27.1-2-obj/i386/ 
default/.
   LD      /usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86/ 
built-in.o
   CC [M]  /usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86/svm.o
In file included from /usr/src/packages/BUILD/kvm-77/suse-kernel/ 
default/x86/svm.c:16:
/usr/src/packages/BUILD/kvm-77/suse-kernel/default/include/linux/ 
kvm_host.h:128: error: field 'mmu_notifier' has incomplete type
make[5]: *** [/usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86/ 
svm.o] Error 1
make[4]: *** [/usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86]  
Error 2
make[3]: *** [_module_/usr/src/packages/BUILD/kvm-77/suse-kernel/ 
default] Error 2
make[2]: *** [sub-make] Error 2
make[1]: *** [all] Error 2
make[1]: Leaving directory `/usr/src/linux-2.6.27.1-2-obj/i386/default'
make: *** [all] Error 2
error: Bad exit status from /var/tmp/rpm-tmp.20019 (%build)

When I remove the struct references it breaks later on due to  
missing(?) inline functions.

Alex

Re: Build failure w/o mmu notifiers

[Avi Kivity]

Alexander Graf wrote:
>
> On 18.10.2008, at 12:51, Avi Kivity wrote:
>
>> Alexander Graf wrote:
>>>
>>> So if I don't select kvm in the kernel (either as module or compiled 
>>> in) I can't build an external module providing kvm's functionality? 
>>> That doesn't seem really useful to me...
>>>
>>
>> The external module hackball should detect that you don't have 
>> CONFIG_MMU_NOTIFIERS set and supply some compatibility glue.  What 
>> error are you seeing?
>
> Basically struct mmu_notifier is not found, but requested by the code:
>
> rm -f include/asm include-compat/asm
> ln -sf asm-x86 include/asm
> ln -sf asm-x86 include-compat/asm
> make -C /usr/src/linux-obj/i586/default M=`pwd` \
>         LINUXINCLUDE="-I`pwd`/include -Iinclude \
>         -Iinclude2 -I/lib/modules/2.6.27.1-2-default/source/include \
>         -Iarch/x86/include -I`pwd`/include-compat \
>         -include include/linux/autoconf.h \
>         -include `pwd`/x86/external-module-compat.h "
> make[1]: Entering directory `/usr/src/linux-2.6.27.1-2-obj/i386/default'
> make -C ../../../linux-2.6.27.1-2 
> O=/usr/src/linux-2.6.27.1-2-obj/i386/default/.
>   LD      
> /usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86/built-in.o
>   CC [M]  /usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86/svm.o
> In file included from 
> /usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86/svm.c:16:
> /usr/src/packages/BUILD/kvm-77/suse-kernel/default/include/linux/kvm_host.h:128: 
> error: field 'mmu_notifier' has incomplete type
> make[5]: *** 
> [/usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86/svm.o] Error 1
> make[4]: *** [/usr/src/packages/BUILD/kvm-77/suse-kernel/default/x86] 
> Error 2
> make[3]: *** 
> [_module_/usr/src/packages/BUILD/kvm-77/suse-kernel/default] Error 2
> make[2]: *** [sub-make] Error 2
> make[1]: *** [all] Error 2
> make[1]: Leaving directory `/usr/src/linux-2.6.27.1-2-obj/i386/default'
> make: *** [all] Error 2
> error: Bad exit status from /var/tmp/rpm-tmp.20019 (%build)
>
> When I remove the struct references it breaks later on due to 
> missing(?) inline functions.
>

Yes, there is an alternate definition in 
kernel/include-compat/linux/mmu_notifier.h, but it doesn't get included 
since the host's mmu_notifier.h has priority; and the host doesn't 
define the structure if !CONFIG_MMU_NOTIFIERS.

I recommend configuring the host with KVM and throwing the modules away 
if you want the external module.  You'll get better functionality so 
it's worth the minor hassle.

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

Re: Build failure w/o mmu notifiers

[Nikola Ciprich]

[-- Attachment #1: Type: text/plain, Size: 2057 bytes --]

Hi,
I've been stumbling to same problems building kernel packages for our distro -
I've made small patches which allow enabling MMU notifier and also preempt notifiers
on kernel with KVM disabled (to allow building external always fresh KVM).
I'm attaching those, hope it helps.
Actually, Avi, do You thing souch patches could be pushed upstream? It doesn't
hurt anything to have such a choice no?
If so, I can send git style patches ;)
regards
nik

On Sat, Oct 18, 2008 at 02:17:27AM +0800, Sheng Yang wrote:
> On Fri, Oct 17, 2008 at 07:47:39PM +0200, Alexander Graf wrote:
> >
> > On 17.10.2008, at 19:25, Sheng Yang wrote:
> >
> >> On Fri, Oct 17, 2008 at 06:34:35PM +0200, Alexander Graf wrote:
> >>> Hi,
> >>>
> >>> I'm currently experiencing build failures when CONFIG_MMU_NOTIFIERS  
> >>> is
> >>> not set. Is this intended? If so, it might be nice to put a  
> >>> configure-
> >>> check or #error somewhere to tell the user that enabling mmu  
> >>> notifiers
> >>> became mandatory.
> >>
> >> Yeah, I think it's intended. In fact, it was selected by KVM
> >> , so if you compile a kernel with KVM, I think it would work...
> >
> > Well - it makes it pretty hard to build KVM as an external module (which 
> > I prefer due to many reasons) and I've actually had a problem to find the 
> > option in make menuconfig somewhere - is it even selectable?
> 
> CONFIG_MMU_NOITFIER? No... It's automatically selected, if you select KVM,
> either in-kernel or module. Please refer to arch/x86/kvm/Kconfig.
> --
> regards
> Yang, Sheng
> >
> > Alex
> >
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

-- 
-------------------------------------
Nikola CIPRICH
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-------------------------------------

[-- Attachment #2: linux-2.6.25-enable-preempt-notifiers.diff --]
[-- Type: text/plain, Size: 684 bytes --]

diff -Naur linux-2.6.25/init/Kconfig linux-2.6.25-enable-preempt-notifiers/init/Kconfig
--- linux-2.6.25/init/Kconfig	2008-06-10 02:51:26.000000000 -0400
+++ linux-2.6.25-enable-preempt-notifiers/init/Kconfig	2008-06-10 03:09:18.000000000 -0400
@@ -800,6 +800,11 @@
 	  /proc/kpagecount, and /proc/kpageflags. Disabling these
           interfaces will reduce the size of the kernel by approximately 4kb.
 
+config PREEMPT_NOTIFIERS
+	bool "Enable preempt notifiers"
+	help
+	  Enable preempt notifiers
+
 endmenu		# General setup
 
 config SLABINFO
@@ -913,9 +918,6 @@
 
 source "block/Kconfig"
 
-config PREEMPT_NOTIFIERS
-	bool
-
 config CLASSIC_RCU
 	def_bool !PREEMPT_RCU
 	help

[-- Attachment #3: linux-2.6.27-enable-mmu-notifier.diff --]
[-- Type: text/plain, Size: 373 bytes --]

diff -Naur linux-2.6.27/mm/Kconfig linux-2.6.27-enable-mmu-notifier/mm/Kconfig
--- linux-2.6.27/mm/Kconfig	2008-10-10 00:13:53.000000000 +0200
+++ linux-2.6.27-enable-mmu-notifier/mm/Kconfig	2008-10-12 15:10:21.000000000 +0200
@@ -207,4 +207,7 @@
 	depends on !ARCH_NO_VIRT_TO_BUS
 
 config MMU_NOTIFIER
-	bool
+	bool "Enable MMU notifier"
+	help
+	  Enable MMU notifier
+

Re: Build failure w/o mmu notifiers

[Avi Kivity]

Nikola Ciprich wrote:
> Hi,
> I've been stumbling to same problems building kernel packages for our distro -
> I've made small patches which allow enabling MMU notifier and also preempt notifiers
> on kernel with KVM disabled (to allow building external always fresh KVM).
> I'm attaching those, hope it helps.
> Actually, Avi, do You thing souch patches could be pushed upstream? It doesn't
> hurt anything to have such a choice no?
>   

More choices to confuse users; and these choices aren't helpful for 
ordinary builds (which don't have external modules).


You can always select KVM and ignore the modules generated.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.