Hi Russel,
I have a battery of configs for compile testing and for some time I've
been seeing the following compilation error with nommu config (attached)
arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
use in this function)
crash_size, SECTION_SIZE);
I didn't get to look what is going on here, maybe my config is just too
artificial but the primary reason is that SECTION_SIZE is not defined in
pgtable-nommu.h. To be honest I am not familiar with nommu very much and
it smells like the whole reserve_crashkernel doesn't really make any
sense on those configs. Could you have a look what is the best fix
please?
--
Michal Hocko
SUSE Labs
On Fri, Aug 18, 2017 at 01:24:02PM +0200, Michal Hocko wrote:
> Hi Russel,
> I have a battery of configs for compile testing and for some time I've
> been seeing the following compilation error with nommu config (attached)
>
> arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
> arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
> use in this function)
> crash_size, SECTION_SIZE);
>
> I didn't get to look what is going on here, maybe my config is just too
> artificial but the primary reason is that SECTION_SIZE is not defined in
> pgtable-nommu.h. To be honest I am not familiar with nommu very much and
> it smells like the whole reserve_crashkernel doesn't really make any
> sense on those configs. Could you have a look what is the best fix
> please?
Hi,
I suspect that mach-netx has never been tested in nommu configurations
(ditto for many of the older platforms, which pre-date merging nommu
support.)
Maybe the best solution is to make these old platforms depend on MMU.
However, I'm wondering whether kexec makes sense for !MMU - that's
probably something that hasn't been tested and doesn't actually work.
So maybe another approach would be to make kexec depend on MMU for
ARM - but I'm afraid I don't really know.
I only have very limited nommu experience.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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On Thu 24-08-17 17:17:41, Russell King - ARM Linux wrote:
> On Fri, Aug 18, 2017 at 01:24:02PM +0200, Michal Hocko wrote:
> > Hi Russel,
> > I have a battery of configs for compile testing and for some time I've
> > been seeing the following compilation error with nommu config (attached)
> >
> > arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
> > arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
> > use in this function)
> > crash_size, SECTION_SIZE);
> >
> > I didn't get to look what is going on here, maybe my config is just too
> > artificial but the primary reason is that SECTION_SIZE is not defined in
> > pgtable-nommu.h. To be honest I am not familiar with nommu very much and
> > it smells like the whole reserve_crashkernel doesn't really make any
> > sense on those configs. Could you have a look what is the best fix
> > please?
>
> Hi,
>
> I suspect that mach-netx has never been tested in nommu configurations
> (ditto for many of the older platforms, which pre-date merging nommu
> support.)
>
> Maybe the best solution is to make these old platforms depend on MMU.
>
> However, I'm wondering whether kexec makes sense for !MMU - that's
> probably something that hasn't been tested and doesn't actually work.
> So maybe another approach would be to make kexec depend on MMU for
> ARM - but I'm afraid I don't really know.
Yeah, I've disabled KEXEC in my testing config. All I do care about is
to test nommu specific code paths in MM code.
> I only have very limited nommu experience.
me too
So what would you say about the following?
---
>From 2707f3bf00181bbc9dcf6a1f287eb7369141e955 Mon Sep 17 00:00:00 2001
From: Michal Hocko <[email protected]>
Date: Fri, 25 Aug 2017 08:40:09 +0200
Subject: [PATCH] arm: make kexec depend on MMU
arm nommu config with KEXEC enabled doesn't compile
arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
use in this function)
crash_size, SECTION_SIZE);
since 61603016e212 ("ARM: kexec: fix crashkernel= handling") which is
over one year without anybody noticing. I have only noticed beause of
my testing nommu config which somehow gained CONFIG_KEXEC without
an intention. This suggests that nobody is actually using KEXEC
on nommu ARM configs. It is even a question whether kexec works with
nommu.
Make KEXEC depend on MMU to make this clear. If somebody wants to enable
there will be probably more things to take care.
Signed-off-by: Michal Hocko <[email protected]>
---
arch/arm/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 3f4aa9179337..c8603195d7fc 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -2003,6 +2003,7 @@ config KEXEC
bool "Kexec system call (EXPERIMENTAL)"
depends on (!SMP || PM_SLEEP_SMP)
depends on !CPU_V7M
+ depends on MMU
select KEXEC_CORE
help
kexec is a system call that implements the ability to shutdown your
--
2.13.2
--
Michal Hocko
SUSE Labs
On Fri 25-08-17 08:45:40, Michal Hocko wrote:
> On Thu 24-08-17 17:17:41, Russell King - ARM Linux wrote:
> > On Fri, Aug 18, 2017 at 01:24:02PM +0200, Michal Hocko wrote:
> > > Hi Russel,
> > > I have a battery of configs for compile testing and for some time I've
> > > been seeing the following compilation error with nommu config (attached)
> > >
> > > arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
> > > arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
> > > use in this function)
> > > crash_size, SECTION_SIZE);
> > >
> > > I didn't get to look what is going on here, maybe my config is just too
> > > artificial but the primary reason is that SECTION_SIZE is not defined in
> > > pgtable-nommu.h. To be honest I am not familiar with nommu very much and
> > > it smells like the whole reserve_crashkernel doesn't really make any
> > > sense on those configs. Could you have a look what is the best fix
> > > please?
> >
> > Hi,
> >
> > I suspect that mach-netx has never been tested in nommu configurations
> > (ditto for many of the older platforms, which pre-date merging nommu
> > support.)
> >
> > Maybe the best solution is to make these old platforms depend on MMU.
> >
> > However, I'm wondering whether kexec makes sense for !MMU - that's
> > probably something that hasn't been tested and doesn't actually work.
> > So maybe another approach would be to make kexec depend on MMU for
> > ARM - but I'm afraid I don't really know.
>
> Yeah, I've disabled KEXEC in my testing config. All I do care about is
> to test nommu specific code paths in MM code.
>
> > I only have very limited nommu experience.
>
> me too
>
> So what would you say about the following?
It's been some time and it seems this has fallen between cracks. Is this
worth puruing or I should just forget about it and drop it on the floor?
> ---
> From 2707f3bf00181bbc9dcf6a1f287eb7369141e955 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <[email protected]>
> Date: Fri, 25 Aug 2017 08:40:09 +0200
> Subject: [PATCH] arm: make kexec depend on MMU
>
> arm nommu config with KEXEC enabled doesn't compile
> arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
> arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
> use in this function)
> crash_size, SECTION_SIZE);
>
> since 61603016e212 ("ARM: kexec: fix crashkernel= handling") which is
> over one year without anybody noticing. I have only noticed beause of
> my testing nommu config which somehow gained CONFIG_KEXEC without
> an intention. This suggests that nobody is actually using KEXEC
> on nommu ARM configs. It is even a question whether kexec works with
> nommu.
>
> Make KEXEC depend on MMU to make this clear. If somebody wants to enable
> there will be probably more things to take care.
>
> Signed-off-by: Michal Hocko <[email protected]>
> ---
> arch/arm/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 3f4aa9179337..c8603195d7fc 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -2003,6 +2003,7 @@ config KEXEC
> bool "Kexec system call (EXPERIMENTAL)"
> depends on (!SMP || PM_SLEEP_SMP)
> depends on !CPU_V7M
> + depends on MMU
> select KEXEC_CORE
> help
> kexec is a system call that implements the ability to shutdown your
> --
> 2.13.2
>
> --
> Michal Hocko
> SUSE Labs
--
Michal Hocko
SUSE Labs
Hi Michal,
On 06.04.2018 11:56, Michal Hocko wrote:
> On Fri 25-08-17 08:45:40, Michal Hocko wrote:
>> On Thu 24-08-17 17:17:41, Russell King - ARM Linux wrote:
>> > On Fri, Aug 18, 2017 at 01:24:02PM +0200, Michal Hocko wrote:
>> > > Hi Russel,
>> > > I have a battery of configs for compile testing and for some time I've
>> > > been seeing the following compilation error with nommu config (attached)
>> > >
>> > > arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
>> > > arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
>> > > use in this function)
>> > > crash_size, SECTION_SIZE);
>> > >
>> > > I didn't get to look what is going on here, maybe my config is just too
>> > > artificial but the primary reason is that SECTION_SIZE is not defined in
>> > > pgtable-nommu.h. To be honest I am not familiar with nommu very much and
>> > > it smells like the whole reserve_crashkernel doesn't really make any
>> > > sense on those configs. Could you have a look what is the best fix
>> > > please?
>> >
>> > Hi,
>> >
>> > I suspect that mach-netx has never been tested in nommu configurations
>> > (ditto for many of the older platforms, which pre-date merging nommu
>> > support.)
>> >
>> > Maybe the best solution is to make these old platforms depend on MMU.
>> >
>> > However, I'm wondering whether kexec makes sense for !MMU - that's
>> > probably something that hasn't been tested and doesn't actually work.
>> > So maybe another approach would be to make kexec depend on MMU for
>> > ARM - but I'm afraid I don't really know.
>>
>> Yeah, I've disabled KEXEC in my testing config. All I do care about is
>> to test nommu specific code paths in MM code.
>>
>> > I only have very limited nommu experience.
>>
>> me too
>>
>> So what would you say about the following?
>
> It's been some time and it seems this has fallen between cracks. Is this
> worth puruing or I should just forget about it and drop it on the floor?
I actually came across this issue during some randconfig testing. Your
change looks good to me:
Reviewed-by: Stefan Agner <[email protected]>
Fixes for the ARM core usually go through Russell's patch tracker, did
you submit you patch there?
See also:
https://www.arm.linux.org.uk/developer/patches/info.php
--
Stefan
>> ---
>> From 2707f3bf00181bbc9dcf6a1f287eb7369141e955 Mon Sep 17 00:00:00 2001
>> From: Michal Hocko <[email protected]>
>> Date: Fri, 25 Aug 2017 08:40:09 +0200
>> Subject: [PATCH] arm: make kexec depend on MMU
>>
>> arm nommu config with KEXEC enabled doesn't compile
>> arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
>> arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
>> use in this function)
>> crash_size, SECTION_SIZE);
>>
>> since 61603016e212 ("ARM: kexec: fix crashkernel= handling") which is
>> over one year without anybody noticing. I have only noticed beause of
>> my testing nommu config which somehow gained CONFIG_KEXEC without
>> an intention. This suggests that nobody is actually using KEXEC
>> on nommu ARM configs. It is even a question whether kexec works with
>> nommu.
>>
>> Make KEXEC depend on MMU to make this clear. If somebody wants to enable
>> there will be probably more things to take care.
>>
>> Signed-off-by: Michal Hocko <[email protected]>
>> ---
>> arch/arm/Kconfig | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> index 3f4aa9179337..c8603195d7fc 100644
>> --- a/arch/arm/Kconfig
>> +++ b/arch/arm/Kconfig
>> @@ -2003,6 +2003,7 @@ config KEXEC
>> bool "Kexec system call (EXPERIMENTAL)"
>> depends on (!SMP || PM_SLEEP_SMP)
>> depends on !CPU_V7M
>> + depends on MMU
>> select KEXEC_CORE
>> help
>> kexec is a system call that implements the ability to shutdown your
>> --
>> 2.13.2
>>
>> --
>> Michal Hocko
>> SUSE Labs
On Tue 05-03-19 23:08:45, Stefan Agner wrote:
> Hi Michal,
>
> On 06.04.2018 11:56, Michal Hocko wrote:
> > On Fri 25-08-17 08:45:40, Michal Hocko wrote:
> >> On Thu 24-08-17 17:17:41, Russell King - ARM Linux wrote:
> >> > On Fri, Aug 18, 2017 at 01:24:02PM +0200, Michal Hocko wrote:
> >> > > Hi Russel,
> >> > > I have a battery of configs for compile testing and for some time I've
> >> > > been seeing the following compilation error with nommu config (attached)
> >> > >
> >> > > arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
> >> > > arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
> >> > > use in this function)
> >> > > crash_size, SECTION_SIZE);
> >> > >
> >> > > I didn't get to look what is going on here, maybe my config is just too
> >> > > artificial but the primary reason is that SECTION_SIZE is not defined in
> >> > > pgtable-nommu.h. To be honest I am not familiar with nommu very much and
> >> > > it smells like the whole reserve_crashkernel doesn't really make any
> >> > > sense on those configs. Could you have a look what is the best fix
> >> > > please?
> >> >
> >> > Hi,
> >> >
> >> > I suspect that mach-netx has never been tested in nommu configurations
> >> > (ditto for many of the older platforms, which pre-date merging nommu
> >> > support.)
> >> >
> >> > Maybe the best solution is to make these old platforms depend on MMU.
> >> >
> >> > However, I'm wondering whether kexec makes sense for !MMU - that's
> >> > probably something that hasn't been tested and doesn't actually work.
> >> > So maybe another approach would be to make kexec depend on MMU for
> >> > ARM - but I'm afraid I don't really know.
> >>
> >> Yeah, I've disabled KEXEC in my testing config. All I do care about is
> >> to test nommu specific code paths in MM code.
> >>
> >> > I only have very limited nommu experience.
> >>
> >> me too
> >>
> >> So what would you say about the following?
> >
> > It's been some time and it seems this has fallen between cracks. Is this
> > worth puruing or I should just forget about it and drop it on the floor?
>
> I actually came across this issue during some randconfig testing. Your
> change looks good to me:
>
> Reviewed-by: Stefan Agner <[email protected]>
>
> Fixes for the ARM core usually go through Russell's patch tracker, did
> you submit you patch there?
>
> See also:
> https://www.arm.linux.org.uk/developer/patches/info.php
Thanks! I am quite busy though so please feel free to resubmit if you
feel this is worth it.
> --
> Stefan
>
> >> ---
> >> From 2707f3bf00181bbc9dcf6a1f287eb7369141e955 Mon Sep 17 00:00:00 2001
> >> From: Michal Hocko <[email protected]>
> >> Date: Fri, 25 Aug 2017 08:40:09 +0200
> >> Subject: [PATCH] arm: make kexec depend on MMU
> >>
> >> arm nommu config with KEXEC enabled doesn't compile
> >> arch/arm/kernel/setup.c: In function 'reserve_crashkernel':
> >> arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first
> >> use in this function)
> >> crash_size, SECTION_SIZE);
> >>
> >> since 61603016e212 ("ARM: kexec: fix crashkernel= handling") which is
> >> over one year without anybody noticing. I have only noticed beause of
> >> my testing nommu config which somehow gained CONFIG_KEXEC without
> >> an intention. This suggests that nobody is actually using KEXEC
> >> on nommu ARM configs. It is even a question whether kexec works with
> >> nommu.
> >>
> >> Make KEXEC depend on MMU to make this clear. If somebody wants to enable
> >> there will be probably more things to take care.
> >>
> >> Signed-off-by: Michal Hocko <[email protected]>
> >> ---
> >> arch/arm/Kconfig | 1 +
> >> 1 file changed, 1 insertion(+)
> >>
> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> >> index 3f4aa9179337..c8603195d7fc 100644
> >> --- a/arch/arm/Kconfig
> >> +++ b/arch/arm/Kconfig
> >> @@ -2003,6 +2003,7 @@ config KEXEC
> >> bool "Kexec system call (EXPERIMENTAL)"
> >> depends on (!SMP || PM_SLEEP_SMP)
> >> depends on !CPU_V7M
> >> + depends on MMU
> >> select KEXEC_CORE
> >> help
> >> kexec is a system call that implements the ability to shutdown your
> >> --
> >> 2.13.2
> >>
> >> --
> >> Michal Hocko
> >> SUSE Labs
--
Michal Hocko
SUSE Labs