Re: [PATCH] Raise the minimum GCC version to 5.2

From: Andy Shevchenko
Date: Tue May 04 2021 - 09:25:29 EST

On Mon, May 3, 2021 at 12:29 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Mon, May 3, 2021 at 9:35 AM Alexander Dahl <ada@xxxxxxxxxxx> wrote:
> >
> > Desktops and servers are all nice, however I just want to make you
> > aware, there are embedded users forced to stick to older cross
> > toolchains for different reasons as well, e.g. in industrial
> > environment. :-)
> >
> > This is no show stopper for us, I just wanted to let you be aware.
> Can you be more specific about what scenarios you are thinking of,
> what the motivations are for using an old compiler with a new kernel
> on embedded systems, and what you think a realistic maximum
> time would be between compiler updates?
> One scenario that I've seen previously is where user space and
> kernel are built together as a source based distribution (OE, buildroot,
> openwrt, ...), and the compiler is picked to match the original sources
> of the user space because that is best tested, but the same compiler
> then gets used to build the kernel as well because that is the default
> in the build environment.
> There are two problems I see with this logic:
> - Running the latest kernel to avoid security problems is of course
> a good idea, but if one runs that with ten year old user space that
> is never updated, the system is likely to end up just as insecure.
> Not all bugs are in the kernel.
> - The same logic that applies to ancient user space staying with
> an ancient compiler (it's better tested in this combination) also
> applies to the kernel: running the latest kernel on an old compiler
> is something that few people test, and tends to run into more bugs
> than using the compiler that other developers used to test that
> kernel.

I understand that you are talking about embedded, but it you stuck
with a distro (esp. LTS one, like CentOS 7.x), you have gcc 4.8.5
there for everything, but they have got security updates. Seems if you
are with a distro you have to stick with its kernel with all pros and
cons of such an approach.

With Best Regards,
Andy Shevchenko