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
