* nommu build failures on ARM in linux-next
@ 2014-05-29 23:40 ` Russell King - ARM Linux
0 siblings, 0 replies; 14+ messages in thread
From: Russell King - ARM Linux @ 2014-05-29 23:40 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, May 29, 2014 at 07:55:34PM +0100, Russell King - ARM Linux wrote:
> On Thu, May 29, 2014 at 12:53:51PM -0400, Paul Gortmaker wrote:
> > Hi Russell,
> >
> > The allnoconfig builds in linux-next fail because __clear_cr
> > lives in mmu.c without any stub or similar in nommu.c
> >
> > Introduced by:
> >
> > commit 247e4fff3aa927ad069447e6da05bb966b70dece
> > Author: Russell King <rmk+kernel@arm.linux.org.uk>
> > Date: Sun Apr 13 18:57:29 2014 +0100
> >
> > ARM: provide common method to clear bits in CPU control register
> >
> > Sample failure:
> > http://kisskb.ellerman.id.au/kisskb/buildresult/11264405/
>
> ALIGNMENT_TRAP depends on CPU_CP15_MMU, so it's quite reasonable that
> __clear_cr should exist in this case - but it doesn't because it's in
> mmu.c. I guess we need __clear_cr moved to arch/arm/kernel/setup.c.
I've been looking at doing this, and while it can be done by applying
a patch on top, that's not my preferred solution.
However, my preferred solution (which is to fix the commit) needs a bit
of rework of the patch series, and given the number of patches I'm
carrying right now, I'm just going to drop the branch out of linux-next
and hold it off until the following merge window instead.
Even so, I suspect even with this build problem solved, that's not going
to be the end of the story for noMMU breakage... it's certainly something
that gets very little testing by anyone. I suspect it should be removed
from the mainline kernel tree rather than being a constant source of these
kinds of problems.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: nommu build failures on ARM in linux-next
2014-05-29 23:40 ` Russell King - ARM Linux
@ 2014-05-30 0:05 ` Paul Gortmaker
-1 siblings, 0 replies; 14+ messages in thread
From: Paul Gortmaker @ 2014-05-30 0:05 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: linux-next@vger.kernel.org, linux-arm-kernel@lists.infradead.org
[Re: nommu build failures on ARM in linux-next] On 30/05/2014 (Fri 00:40) Russell King - ARM Linux wrote:
> On Thu, May 29, 2014 at 07:55:34PM +0100, Russell King - ARM Linux wrote:
> > On Thu, May 29, 2014 at 12:53:51PM -0400, Paul Gortmaker wrote:
> > > Hi Russell,
> > >
> > > The allnoconfig builds in linux-next fail because __clear_cr
> > > lives in mmu.c without any stub or similar in nommu.c
> > >
> > > Introduced by:
> > >
> > > commit 247e4fff3aa927ad069447e6da05bb966b70dece
> > > Author: Russell King <rmk+kernel@arm.linux.org.uk>
> > > Date: Sun Apr 13 18:57:29 2014 +0100
> > >
> > > ARM: provide common method to clear bits in CPU control register
> > >
> > > Sample failure:
> > > http://kisskb.ellerman.id.au/kisskb/buildresult/11264405/
> >
> > ALIGNMENT_TRAP depends on CPU_CP15_MMU, so it's quite reasonable that
> > __clear_cr should exist in this case - but it doesn't because it's in
> > mmu.c. I guess we need __clear_cr moved to arch/arm/kernel/setup.c.
>
> I've been looking at doing this, and while it can be done by applying
> a patch on top, that's not my preferred solution.
>
> However, my preferred solution (which is to fix the commit) needs a bit
> of rework of the patch series, and given the number of patches I'm
> carrying right now, I'm just going to drop the branch out of linux-next
> and hold it off until the following merge window instead.
>
> Even so, I suspect even with this build problem solved, that's not going
> to be the end of the story for noMMU breakage... it's certainly something
> that gets very little testing by anyone. I suspect it should be removed
> from the mainline kernel tree rather than being a constant source of these
> kinds of problems.
One doesn't have to look very far to see that I'm in favour of pushing
obsolete options/drivers/subsystems off a cliff if I can get away with
it, so that we don't get crushed under our own weight/complexity.
So if you really think it is time for ARM noMMU to go, I'll volunteer to
craft up a removal series for you for 3.17 -- just say the word.
Paul.
--
>
> --
> FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
> improving, and getting towards what was expected from it.
^ permalink raw reply [flat|nested] 14+ messages in thread
* nommu build failures on ARM in linux-next
@ 2014-05-30 0:05 ` Paul Gortmaker
0 siblings, 0 replies; 14+ messages in thread
From: Paul Gortmaker @ 2014-05-30 0:05 UTC (permalink / raw)
To: linux-arm-kernel
[Re: nommu build failures on ARM in linux-next] On 30/05/2014 (Fri 00:40) Russell King - ARM Linux wrote:
> On Thu, May 29, 2014 at 07:55:34PM +0100, Russell King - ARM Linux wrote:
> > On Thu, May 29, 2014 at 12:53:51PM -0400, Paul Gortmaker wrote:
> > > Hi Russell,
> > >
> > > The allnoconfig builds in linux-next fail because __clear_cr
> > > lives in mmu.c without any stub or similar in nommu.c
> > >
> > > Introduced by:
> > >
> > > commit 247e4fff3aa927ad069447e6da05bb966b70dece
> > > Author: Russell King <rmk+kernel@arm.linux.org.uk>
> > > Date: Sun Apr 13 18:57:29 2014 +0100
> > >
> > > ARM: provide common method to clear bits in CPU control register
> > >
> > > Sample failure:
> > > http://kisskb.ellerman.id.au/kisskb/buildresult/11264405/
> >
> > ALIGNMENT_TRAP depends on CPU_CP15_MMU, so it's quite reasonable that
> > __clear_cr should exist in this case - but it doesn't because it's in
> > mmu.c. I guess we need __clear_cr moved to arch/arm/kernel/setup.c.
>
> I've been looking at doing this, and while it can be done by applying
> a patch on top, that's not my preferred solution.
>
> However, my preferred solution (which is to fix the commit) needs a bit
> of rework of the patch series, and given the number of patches I'm
> carrying right now, I'm just going to drop the branch out of linux-next
> and hold it off until the following merge window instead.
>
> Even so, I suspect even with this build problem solved, that's not going
> to be the end of the story for noMMU breakage... it's certainly something
> that gets very little testing by anyone. I suspect it should be removed
> from the mainline kernel tree rather than being a constant source of these
> kinds of problems.
One doesn't have to look very far to see that I'm in favour of pushing
obsolete options/drivers/subsystems off a cliff if I can get away with
it, so that we don't get crushed under our own weight/complexity.
So if you really think it is time for ARM noMMU to go, I'll volunteer to
craft up a removal series for you for 3.17 -- just say the word.
Paul.
--
>
> --
> FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
> improving, and getting towards what was expected from it.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: nommu build failures on ARM in linux-next
2014-05-29 23:40 ` Russell King - ARM Linux
@ 2014-05-30 7:58 ` Robert Schwebel
-1 siblings, 0 replies; 14+ messages in thread
From: Robert Schwebel @ 2014-05-30 7:58 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Paul Gortmaker, linux-next@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
On Fri, May 30, 2014 at 12:40:12AM +0100, Russell King - ARM Linux wrote:
> Even so, I suspect even with this build problem solved, that's not going
> to be the end of the story for noMMU breakage... it's certainly something
> that gets very little testing by anyone. I suspect it should be removed
> from the mainline kernel tree rather than being a constant source of these
> kinds of problems.
Uwe can have a look next week.
Taken that it took *ages* to get Cortex-M3 support in mainline and taken
that it might become more interesting with the upcoming generation of
FPGAs and Cortex-A SoCs with an additional Cortex-M, it would be pretty
bad to lose NOMMU again.
rsc
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
^ permalink raw reply [flat|nested] 14+ messages in thread
* nommu build failures on ARM in linux-next
@ 2014-05-30 7:58 ` Robert Schwebel
0 siblings, 0 replies; 14+ messages in thread
From: Robert Schwebel @ 2014-05-30 7:58 UTC (permalink / raw)
To: linux-arm-kernel
On Fri, May 30, 2014 at 12:40:12AM +0100, Russell King - ARM Linux wrote:
> Even so, I suspect even with this build problem solved, that's not going
> to be the end of the story for noMMU breakage... it's certainly something
> that gets very little testing by anyone. I suspect it should be removed
> from the mainline kernel tree rather than being a constant source of these
> kinds of problems.
Uwe can have a look next week.
Taken that it took *ages* to get Cortex-M3 support in mainline and taken
that it might become more interesting with the upcoming generation of
FPGAs and Cortex-A SoCs with an additional Cortex-M, it would be pretty
bad to lose NOMMU again.
rsc
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: nommu build failures on ARM in linux-next
2014-05-29 23:40 ` Russell King - ARM Linux
@ 2014-05-30 8:02 ` Uwe Kleine-König
-1 siblings, 0 replies; 14+ messages in thread
From: Uwe Kleine-König @ 2014-05-30 8:02 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Paul Gortmaker, linux-next@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, Jonathan Austin,
Kevin Hilman, kernel
Hello,
[adding a few people to Cc]
On Fri, May 30, 2014 at 12:40:12AM +0100, Russell King - ARM Linux wrote:
> On Thu, May 29, 2014 at 07:55:34PM +0100, Russell King - ARM Linux wrote:
> > On Thu, May 29, 2014 at 12:53:51PM -0400, Paul Gortmaker wrote:
> > > Hi Russell,
> > >
> > > The allnoconfig builds in linux-next fail because __clear_cr
> > > lives in mmu.c without any stub or similar in nommu.c
> > >
> > > Introduced by:
> > >
> > > commit 247e4fff3aa927ad069447e6da05bb966b70dece
> > > Author: Russell King <rmk+kernel@arm.linux.org.uk>
> > > Date: Sun Apr 13 18:57:29 2014 +0100
> > >
> > > ARM: provide common method to clear bits in CPU control register
> > >
> > > Sample failure:
> > > http://kisskb.ellerman.id.au/kisskb/buildresult/11264405/
> >
> > ALIGNMENT_TRAP depends on CPU_CP15_MMU, so it's quite reasonable that
> > __clear_cr should exist in this case - but it doesn't because it's in
> > mmu.c. I guess we need __clear_cr moved to arch/arm/kernel/setup.c.
>
> I've been looking at doing this, and while it can be done by applying
> a patch on top, that's not my preferred solution.
>
> However, my preferred solution (which is to fix the commit) needs a bit
> of rework of the patch series, and given the number of patches I'm
> carrying right now, I'm just going to drop the branch out of linux-next
> and hold it off until the following merge window instead.
>
> Even so, I suspect even with this build problem solved, that's not going
> to be the end of the story for noMMU breakage... it's certainly something
> that gets very little testing by anyone. I suspect it should be removed
> from the mainline kernel tree rather than being a constant source of these
> kinds of problems.
That would mean that support for Cortex-M3 would die, too, which would
(IMHO) be sad.
Currently the efm32 test in our autobuilder is broken, I will address
that and then keep an eye on it.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 14+ messages in thread
* nommu build failures on ARM in linux-next
@ 2014-05-30 8:02 ` Uwe Kleine-König
0 siblings, 0 replies; 14+ messages in thread
From: Uwe Kleine-König @ 2014-05-30 8:02 UTC (permalink / raw)
To: linux-arm-kernel
Hello,
[adding a few people to Cc]
On Fri, May 30, 2014 at 12:40:12AM +0100, Russell King - ARM Linux wrote:
> On Thu, May 29, 2014 at 07:55:34PM +0100, Russell King - ARM Linux wrote:
> > On Thu, May 29, 2014 at 12:53:51PM -0400, Paul Gortmaker wrote:
> > > Hi Russell,
> > >
> > > The allnoconfig builds in linux-next fail because __clear_cr
> > > lives in mmu.c without any stub or similar in nommu.c
> > >
> > > Introduced by:
> > >
> > > commit 247e4fff3aa927ad069447e6da05bb966b70dece
> > > Author: Russell King <rmk+kernel@arm.linux.org.uk>
> > > Date: Sun Apr 13 18:57:29 2014 +0100
> > >
> > > ARM: provide common method to clear bits in CPU control register
> > >
> > > Sample failure:
> > > http://kisskb.ellerman.id.au/kisskb/buildresult/11264405/
> >
> > ALIGNMENT_TRAP depends on CPU_CP15_MMU, so it's quite reasonable that
> > __clear_cr should exist in this case - but it doesn't because it's in
> > mmu.c. I guess we need __clear_cr moved to arch/arm/kernel/setup.c.
>
> I've been looking at doing this, and while it can be done by applying
> a patch on top, that's not my preferred solution.
>
> However, my preferred solution (which is to fix the commit) needs a bit
> of rework of the patch series, and given the number of patches I'm
> carrying right now, I'm just going to drop the branch out of linux-next
> and hold it off until the following merge window instead.
>
> Even so, I suspect even with this build problem solved, that's not going
> to be the end of the story for noMMU breakage... it's certainly something
> that gets very little testing by anyone. I suspect it should be removed
> from the mainline kernel tree rather than being a constant source of these
> kinds of problems.
That would mean that support for Cortex-M3 would die, too, which would
(IMHO) be sad.
Currently the efm32 test in our autobuilder is broken, I will address
that and then keep an eye on it.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: nommu build failures on ARM in linux-next
2014-05-30 8:02 ` Uwe Kleine-König
@ 2014-06-02 7:19 ` Uwe Kleine-König
-1 siblings, 0 replies; 14+ messages in thread
From: Uwe Kleine-König @ 2014-06-02 7:19 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Jonathan Austin, Kevin Hilman, Paul Gortmaker,
linux-next@vger.kernel.org, kernel,
linux-arm-kernel@lists.infradead.org
Hello,
On Fri, May 30, 2014 at 10:02:57AM +0200, Uwe Kleine-König wrote:
> > Even so, I suspect even with this build problem solved, that's not going
> > to be the end of the story for noMMU breakage... it's certainly something
> > that gets very little testing by anyone. I suspect it should be removed
> > from the mainline kernel tree rather than being a constant source of these
> > kinds of problems.
> That would mean that support for Cortex-M3 would die, too, which would
> (IMHO) be sad.
Just for your information: The problem in question here doesn't affect
ARM-v7M (aka Cortex-M[34]) because the patch only touches areas
protected by #ifdef CONFIG_CPU_CP15 which is off for these machines.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 14+ messages in thread
* nommu build failures on ARM in linux-next
@ 2014-06-02 7:19 ` Uwe Kleine-König
0 siblings, 0 replies; 14+ messages in thread
From: Uwe Kleine-König @ 2014-06-02 7:19 UTC (permalink / raw)
To: linux-arm-kernel
Hello,
On Fri, May 30, 2014 at 10:02:57AM +0200, Uwe Kleine-K?nig wrote:
> > Even so, I suspect even with this build problem solved, that's not going
> > to be the end of the story for noMMU breakage... it's certainly something
> > that gets very little testing by anyone. I suspect it should be removed
> > from the mainline kernel tree rather than being a constant source of these
> > kinds of problems.
> That would mean that support for Cortex-M3 would die, too, which would
> (IMHO) be sad.
Just for your information: The problem in question here doesn't affect
ARM-v7M (aka Cortex-M[34]) because the patch only touches areas
protected by #ifdef CONFIG_CPU_CP15 which is off for these machines.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 14+ messages in thread