[Buildroot] [PATCH] ipkg: needs MMU

[Buildroot] [PATCH] ipkg: needs MMU

[Baruch Siach]

Fixes:
http://autobuild.buildroot.net/results/6cf/6cf75e08795d9ab194ce4e882c0f4858bad979c3/
http://autobuild.buildroot.net/results/964/964d8f694bc7d05b35411eabfbadf40bbf6337ae/
http://autobuild.buildroot.net/results/0f2/0f2cddf89af3ad4330556acd04ab6cb080370e24/

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 package/ipkg/Config.in | 1 +
 1 file changed, 1 insertion(+)

diff --git a/package/ipkg/Config.in b/package/ipkg/Config.in
index 4b2078d9cd70..d93e1d17b3dd 100644
--- a/package/ipkg/Config.in
+++ b/package/ipkg/Config.in
@@ -1,5 +1,6 @@
 config BR2_PACKAGE_IPKG
 	bool "ipkg"
+	depends on BR2_USE_MMU # fork()
 	help
 	  The Itsy Package Installer from handhelds.org
 
-- 
2.8.1

[Buildroot] [PATCH] ipkg: needs MMU

[Thomas Petazzoni]

Hello,

On Tue, 26 Jul 2016 07:00:37 +0300, Baruch Siach wrote:
> Fixes:
> http://autobuild.buildroot.net/results/6cf/6cf75e08795d9ab194ce4e882c0f4858bad979c3/
> http://autobuild.buildroot.net/results/964/964d8f694bc7d05b35411eabfbadf40bbf6337ae/
> http://autobuild.buildroot.net/results/0f2/0f2cddf89af3ad4330556acd04ab6cb080370e24/
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
>  package/ipkg/Config.in | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/package/ipkg/Config.in b/package/ipkg/Config.in
> index 4b2078d9cd70..d93e1d17b3dd 100644
> --- a/package/ipkg/Config.in
> +++ b/package/ipkg/Config.in
> @@ -1,5 +1,6 @@
>  config BR2_PACKAGE_IPKG
>  	bool "ipkg"
> +	depends on BR2_USE_MMU # fork()

I think this needs more investigation, because:

BR2_bfin=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_INIT_NONE=y
# BR2_PACKAGE_BUSYBOX is not set
BR2_PACKAGE_IPKG=y
# BR2_TARGET_ROOTFS_TAR is not set

which is a noMMU configuration, is able to build ipkg just fine.



-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCH] ipkg: needs MMU

[Thomas Petazzoni]

Hello,

Sorry, last e-mail sent mistakenly.

On Tue, 26 Jul 2016 09:59:29 +0200, Thomas Petazzoni wrote:

> I think this needs more investigation, because:
> 
> BR2_bfin=y
> BR2_TOOLCHAIN_EXTERNAL=y
> BR2_INIT_NONE=y
> # BR2_PACKAGE_BUSYBOX is not set
> BR2_PACKAGE_IPKG=y
> # BR2_TARGET_ROOTFS_TAR is not set
> 
> which is a noMMU configuration, is able to build ipkg just fine.

I was indeed a bit surprised to see this patch: we have been having
Blackfin configurations for a long time in the autobuilders, and we
never had to add a BR2_USE_MMU dependency on this package.

So I believe there's something a bit more subtle going on here.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCH] ipkg: needs MMU

[Baruch Siach]

Hi Thomas,

On Tue, Jul 26, 2016 at 10:01:01AM +0200, Thomas Petazzoni wrote:
> On Tue, 26 Jul 2016 09:59:29 +0200, Thomas Petazzoni wrote:
> > I think this needs more investigation, because:
> > 
> > BR2_bfin=y
> > BR2_TOOLCHAIN_EXTERNAL=y
> > BR2_INIT_NONE=y
> > # BR2_PACKAGE_BUSYBOX is not set
> > BR2_PACKAGE_IPKG=y
> > # BR2_TARGET_ROOTFS_TAR is not set
> > 
> > which is a noMMU configuration, is able to build ipkg just fine.
> 
> I was indeed a bit surprised to see this patch: we have been having
> Blackfin configurations for a long time in the autobuilders, and we
> never had to add a BR2_USE_MMU dependency on this package.
> 
> So I believe there's something a bit more subtle going on here.

Right. It's this code from libbb/libbb.h:

/* Cope with mmu-less systems somewhat gracefully */
#if defined(__UCLIBC__) && !defined(__ARCH_HAS_MMU__)
#define fork    vfork
#endif

This breaks musl that does not define __UCLIBC__. I posted an updated patch to 
uses HAVE_FORK instead.

Is there anyone actually using this package anyway? Even its homepage is not 
accessible here (handhelds.org does not resolve).

Thanks for reviewing,
baruch

-- 
     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -

[Buildroot] [PATCH] ipkg: needs MMU

[Thomas Petazzoni]

Hello,

On Tue, 26 Jul 2016 14:15:57 +0300, Baruch Siach wrote:

> Right. It's this code from libbb/libbb.h:
> 
> /* Cope with mmu-less systems somewhat gracefully */
> #if defined(__UCLIBC__) && !defined(__ARCH_HAS_MMU__)
> #define fork    vfork
> #endif
> 
> This breaks musl that does not define __UCLIBC__. I posted an updated patch to 
> uses HAVE_FORK instead.

We don't use musl on any noMMU platform today, so this certainly cannot
explain failures like:

  http://autobuild.buildroot.net/results/6cf/6cf75e08795d9ab194ce4e882c0f4858bad979c3/

(which was the first one mentioned in your commit log), since this
failure happens with uClibc.

Looking at http://autobuild.buildroot.net/?reason=ipkg-0.99.163, I see
(looking only at the failures since the beginning of 2016) :

 * Numerous failures on ARM noMMU (uClibc)
 * Two failures on m68k noMMU (uClibc)
 * An old failure on i686 due to download issue

i.e, none of the failures are caused by a musl-related build.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCH] ipkg: needs MMU

[Baruch Siach]

Hi Thomas,

On Tue, Jul 26, 2016 at 01:48:01PM +0200, Thomas Petazzoni wrote:
> On Tue, 26 Jul 2016 14:15:57 +0300, Baruch Siach wrote:
> > Right. It's this code from libbb/libbb.h:
> > 
> > /* Cope with mmu-less systems somewhat gracefully */
> > #if defined(__UCLIBC__) && !defined(__ARCH_HAS_MMU__)
> > #define fork    vfork
> > #endif
> > 
> > This breaks musl that does not define __UCLIBC__. I posted an updated patch to 
> > uses HAVE_FORK instead.
> 
> We don't use musl on any noMMU platform today, so this certainly cannot
> explain failures like:
> 
>   http://autobuild.buildroot.net/results/6cf/6cf75e08795d9ab194ce4e882c0f4858bad979c3/
> 
> (which was the first one mentioned in your commit log), since this
> failure happens with uClibc.
> 
> Looking at http://autobuild.buildroot.net/?reason=ipkg-0.99.163, I see
> (looking only at the failures since the beginning of 2016) :
> 
>  * Numerous failures on ARM noMMU (uClibc)
>  * Two failures on m68k noMMU (uClibc)
>  * An old failure on i686 due to download issue
> 
> i.e, none of the failures are caused by a musl-related build.

You are right of course, forgive my sloppiness. To be correct for uClibc the 
code should test for __ARCH_USE_MMU__ instead of __ARCH_HAS_MMU__. But testing 
HAVE_FORK is better, I thing, since it also covers other hypothetical MMU-less 
C libraries.

I'll resend the patch with a correct description.

baruch

-- 
     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -

[Buildroot] [PATCH] ipkg: needs MMU

[Thomas Petazzoni]

Hello,

On Tue, 26 Jul 2016 15:14:29 +0300, Baruch Siach wrote:

> You are right of course, forgive my sloppiness. To be correct for uClibc the 
> code should test for __ARCH_USE_MMU__ instead of __ARCH_HAS_MMU__. But testing 
> HAVE_FORK is better, I thing, since it also covers other hypothetical MMU-less 
> C libraries.

Using HAVE_FORK indeed seems better. However, can you verify that it
actually works for MMU-capable platforms?

What worries me is that the code in libbb/ originally comes from
Busybox, which doesn't use autoconf. HAVE_FORK is a #define value
defined by ipkg's autoconf configure script, in config.h, and I'm not
sure if the libbb/ code includes config.h.

So, please make sure that HAVE_FORK is really taken into account when
building on MMU-capable platforms by adding some #error in the #if
defined(HAVE_FORK) test in the libbb code that you're changing.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCH] ipkg: needs MMU

[Baruch Siach]

Hi Thomas,

On Tue, Jul 26, 2016 at 02:52:48PM +0200, Thomas Petazzoni wrote:
> On Tue, 26 Jul 2016 15:14:29 +0300, Baruch Siach wrote:
> > You are right of course, forgive my sloppiness. To be correct for uClibc 
> > the code should test for __ARCH_USE_MMU__ instead of __ARCH_HAS_MMU__. But 
> > testing HAVE_FORK is better, I thing, since it also covers other 
> > hypothetical MMU-less C libraries.
> 
> Using HAVE_FORK indeed seems better. However, can you verify that it
> actually works for MMU-capable platforms?
> 
> What worries me is that the code in libbb/ originally comes from
> Busybox, which doesn't use autoconf. HAVE_FORK is a #define value
> defined by ipkg's autoconf configure script, in config.h, and I'm not
> sure if the libbb/ code includes config.h.
> 
> So, please make sure that HAVE_FORK is really taken into account when
> building on MMU-capable platforms by adding some #error in the #if
> defined(HAVE_FORK) test in the libbb code that you're changing.

I verified that config.h macros are defined in libbb.h before posting the last 
patch, by using another defined macros. I repeated this test as you suggested, 
with HAVE_FORK and the current br-arm-full.config, just to be sure. The #error 
triggers as expected in both tests.

baruch

-- 
     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -

[Buildroot] [PATCH] ipkg: needs MMU

[Thomas Petazzoni]

Hello,

On Tue, 26 Jul 2016 18:08:54 +0300, Baruch Siach wrote:

> I verified that config.h macros are defined in libbb.h before posting the last 
> patch, by using another defined macros. I repeated this test as you suggested, 
> with HAVE_FORK and the current br-arm-full.config, just to be sure. The #error 
> triggers as expected in both tests.

Excellent, thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCH] ipkg: needs MMU

[Khem Raj]

> On Jul 26, 2016, at 5:14 AM, Baruch Siach <baruch@tkos.co.il> wrote:
> 
> Hi Thomas,
> 
> On Tue, Jul 26, 2016 at 01:48:01PM +0200, Thomas Petazzoni wrote:
>> On Tue, 26 Jul 2016 14:15:57 +0300, Baruch Siach wrote:
>>> Right. It's this code from libbb/libbb.h:
>>> 
>>> /* Cope with mmu-less systems somewhat gracefully */
>>> #if defined(__UCLIBC__) && !defined(__ARCH_HAS_MMU__)
>>> #define fork    vfork
>>> #endif
>>> 
>>> This breaks musl that does not define __UCLIBC__. I posted an updated patch to
>>> uses HAVE_FORK instead.
>> 
>> We don't use musl on any noMMU platform today,

SH2 fdpic is available in musl, so in theory you can start :)

>> so this certainly cannot
>> explain failures like:
>> 
>>  http://autobuild.buildroot.net/results/6cf/6cf75e08795d9ab194ce4e882c0f4858bad979c3/
>> 
>> (which was the first one mentioned in your commit log), since this
>> failure happens with uClibc.
>> 
>> Looking at http://autobuild.buildroot.net/?reason=ipkg-0.99.163, I see
>> (looking only at the failures since the beginning of 2016) :
>> 
>> * Numerous failures on ARM noMMU (uClibc)
>> * Two failures on m68k noMMU (uClibc)
>> * An old failure on i686 due to download issue
>> 
>> i.e, none of the failures are caused by a musl-related build.
> 
> You are right of course, forgive my sloppiness. To be correct for uClibc the
> code should test for __ARCH_USE_MMU__ instead of __ARCH_HAS_MMU__. But testing
> HAVE_FORK is better, I thing, since it also covers other hypothetical MMU-less
> C libraries.

ARCH_USE_MMU seems to be sufficient unless there is any other kind of memory
management system that can redefine fork behavior.

is fork the only difference when it comes to nommu, I guess not. So why create an
extra check just for fork.

> 
> I'll resend the patch with a correct description.
> 
> baruch
> 
> --
>     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
> =}------------------------------------------------ooO--U--Ooo------------{=
>   - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

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