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From: Michael Olbrich <m.olbrich@pengutronix.de>
To: ptxdist@pengutronix.de
Subject: Re: [ptxdist] Kernel GCC plugins
Date: Fri, 16 Jul 2021 14:58:09 +0200	[thread overview]
Message-ID: <20210716125809.GC15288@pengutronix.de> (raw)
In-Reply-To: <20210716121151.yz7ksnenssgzosci@falbala.internal.home.lespocky.de>

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

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  reply	other threads:[~2021-07-16 12:58 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CABDcavbMrCE=yXDZ=MSbVCe1AVHX0U1-9XmmgZd0X5HN1J1QXg@mail.gmail.com>
2021-07-16 12:11 ` Alexander Dahl
2021-07-16 12:58   ` Michael Olbrich [this message]
     [not found]   ` <CABDcavYOeVWR+nVkMo4HXxFme=EmK050C383jGbAatD+N8GU3g@mail.gmail.com>
2021-07-16 13:04     ` Michael Olbrich
     [not found]       ` <CABDcavZbjMQdMoQnScC-kmtciA2vKrton+-ztexWSCnYVBXqGQ@mail.gmail.com>
2021-07-20 12:02         ` Michael Olbrich

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