Re: [ptxdist] Kernel GCC plugins

Re: [ptxdist] Kernel GCC plugins

[Alexander Dahl]

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Hei hei,

On Fri, Jul 16, 2021 at 01:32:29PM +0200, Guillermo Rodriguez Garcia wrote:
> I notice that the kernelconfig files changes depending on the host gcc
> version; in particular depending on supported gcc plugins.
> 
> However this does not seem to make much sense -- the kernel will not be
> built using the host gcc; it will be built using the cross compiler from
> the toolchain.
> 
> Is it possible to avoid this?

IIRC this was addressed several times in recent ptxdist versions:

- ptxdist-2021.04.0-14-g533f7709f ("kernel/kernel-template: set PTXDIST_NO_GCC_PLUGINS=1 in _MAKE_ENV as well")
- ptxdist-2021.03.0-69-g7a90f622f ("template: kernel: fix disabling gcc plugins for >= v5.11")
- ptxdist-2021.03.0-33-g114fecbd4 ("kernel: really fix disabling gcc plugins for >= v5.11)
- ptxdist-2021.02.0-41-gd57abb428 ("kernel: fix disabling gcc plugins for >= v5.11")

… and maybe more?

Or is yours another problem?

Greets
Alex

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Re: [ptxdist] Kernel GCC plugins

[Michael Olbrich]

On Fri, Jul 16, 2021 at 02:11:52PM +0200, Alexander Dahl wrote:
> On Fri, Jul 16, 2021 at 01:32:29PM +0200, Guillermo Rodriguez Garcia wrote:
> > I notice that the kernelconfig files changes depending on the host gcc
> > version; in particular depending on supported gcc plugins.
> > 
> > However this does not seem to make much sense -- the kernel will not be
> > built using the host gcc; it will be built using the cross compiler from
> > the toolchain.
> > 
> > Is it possible to avoid this?
> 
> IIRC this was addressed several times in recent ptxdist versions:
> 
> - ptxdist-2021.04.0-14-g533f7709f ("kernel/kernel-template: set PTXDIST_NO_GCC_PLUGINS=1 in _MAKE_ENV as well")
> - ptxdist-2021.03.0-69-g7a90f622f ("template: kernel: fix disabling gcc plugins for >= v5.11")
> - ptxdist-2021.03.0-33-g114fecbd4 ("kernel: really fix disabling gcc plugins for >= v5.11)
> - ptxdist-2021.02.0-41-gd57abb428 ("kernel: fix disabling gcc plugins for >= v5.11")
> 
> … and maybe more?

This started long before that:

ptxdist-2018.11.0-107-gc065184961ab ("kernel: add workaround to keep kernelconfigs stable")

Some more details on what happens here:

The kernel can use gcc plugins to do some tricks while building the kernel.
These plugins are built with the host gcc so at some point (v4.19) a check
was introduced to see if it's actually possible to build the plugins.
If the check passes, then a kconfig symbol is set to 'y' and you can enable
the plugins available for your current target architecture.

This check depends on the host compiler and related stuff, so sometimes the
config changes.
To avoid this, I tries to do some magic to force the check to fail all the
time. Unfortunately this check changed multiple times, so I had to change
PTXdist again because the check stopped failing...

Michael

-- 
Pengutronix e.K.                           |                             |
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Re: [ptxdist] Kernel GCC plugins

[Michael Olbrich]

On Fri, Jul 16, 2021 at 02:45:40PM +0200, Guillermo Rodriguez Garcia wrote:
> El viernes, 16 de julio de 2021, Alexander Dahl <post@lespocky.de> escribió:
> > On Fri, Jul 16, 2021 at 01:32:29PM +0200, Guillermo Rodriguez Garcia wrote:
> > > I notice that the kernelconfig files changes depending on the host gcc
> > > version; in particular depending on supported gcc plugins.
> > >
> > > However this does not seem to make much sense -- the kernel will not be
> > > built using the host gcc; it will be built using the cross compiler from
> > > the toolchain.
> > >
> > > Is it possible to avoid this?
> >
> > IIRC this was addressed several times in recent ptxdist versions:
> >
> > - ptxdist-2021.04.0-14-g533f7709f ("kernel/kernel-template: set
> > PTXDIST_NO_GCC_PLUGINS=1 in _MAKE_ENV as well")
> > - ptxdist-2021.03.0-69-g7a90f622f ("template: kernel: fix disabling gcc
> > plugins for >= v5.11")
> > - ptxdist-2021.03.0-33-g114fecbd4 ("kernel: really fix disabling gcc
> > plugins for >= v5.11)
> > - ptxdist-2021.02.0-41-gd57abb428 ("kernel: fix disabling gcc plugins for
> > >= v5.11")
> >
> > … and maybe more?
> >
> > Or is yours another problem?
> 
> 
> Do I need to do something special for this to work?
> 
> I’m on ptxdist 2021.07.0 so the above fixes should be merged, yet I am
> still having the problem ..

Is PTXCONF_KERNEL_GCC_PLUGINS disabled? And which kernel version? Maybe the
check changed again.

Michael

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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Re: [ptxdist] Kernel GCC plugins

[Michael Olbrich]

Hi,

On Mon, Jul 19, 2021 at 01:45:44PM +0200, Guillermo Rodriguez Garcia wrote:
> El vie, 16 jul 2021 a las 15:04, Michael Olbrich (<m.olbrich@pengutronix.de>)
> escribió:
> > On Fri, Jul 16, 2021 at 02:45:40PM +0200, Guillermo Rodriguez Garcia wrote:
> > > El viernes, 16 de julio de 2021, Alexander Dahl <post@lespocky.de>
> > escribió:
> > > > On Fri, Jul 16, 2021 at 01:32:29PM +0200, Guillermo Rodriguez Garcia
> > wrote:
> > > > > I notice that the kernelconfig files changes depending on the host
> > gcc
> > > > > version; in particular depending on supported gcc plugins.
> > > > >
> > > > > However this does not seem to make much sense -- the kernel will not
> > be
> > > > > built using the host gcc; it will be built using the cross compiler
> > from
> > > > > the toolchain.
> > > > >
> > > > > Is it possible to avoid this?
> > > >
> > > > IIRC this was addressed several times in recent ptxdist versions:
> > > >
> > > > - ptxdist-2021.04.0-14-g533f7709f ("kernel/kernel-template: set
> > > > PTXDIST_NO_GCC_PLUGINS=1 in _MAKE_ENV as well")
> > > > - ptxdist-2021.03.0-69-g7a90f622f ("template: kernel: fix disabling gcc
> > > > plugins for >= v5.11")
> > > > - ptxdist-2021.03.0-33-g114fecbd4 ("kernel: really fix disabling gcc
> > > > plugins for >= v5.11)
> > > > - ptxdist-2021.02.0-41-gd57abb428 ("kernel: fix disabling gcc plugins
> > for
> > > > >= v5.11")
> > > >
> > > > … and maybe more?
> > > >
> > > > Or is yours another problem?
> > >
> > >
> > > Do I need to do something special for this to work?
> > >
> > > I’m on ptxdist 2021.07.0 so the above fixes should be merged, yet I am
> > > still having the problem ..
> >
> > Is PTXCONF_KERNEL_GCC_PLUGINS disabled?
> 
> Yes.

Ok.

> > And which kernel version?
> 
> 
> 5.4.56
> 
> I am rechecking, perhaps I did something wrong in the process.

Or maybe that version has a different check. Looking hat the history, I
definitely checked v4.19 and v5.6. I'm not sure about the versions in
between. Take a look at what scripts/gcc-plugins/Kconfig is doing.

Michael

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
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