Re: [PATCH v3 4/4] kernel hacking: new config CC_OPTIMIZE_FOR_DEBUGGING to apply GCC -Og optimization
From: Changbin Du
Date: Mon Oct 29 2018 - 10:54:57 EST
On Mon, Oct 29, 2018 at 10:16:02PM +0900, Masahiro Yamada wrote:
> On Sun, Oct 28, 2018 at 10:11 PM Changbin Du <changbin.du@xxxxxxxxx> wrote:
> > This will apply GCC '-Og' optimization level which is supported
> > since GCC 4.8. This optimization level offers a reasonable level
> > of optimization while maintaining fast compilation and a good
> > debugging experience. It is similar to '-O1' while perferring
> > to keep debug ability over runtime speed.
> > If enabling this option breaks your kernel, you should either
> > disable this or find a fix (mostly in the arch code). Currently
> > this option has only been tested on x86_64 and arm platform.
> > This option can satisfy people who was searching for a method
> > to disable compiler optimizations so to achieve better kernel
> > debugging experience with kgdb or qemu.
> > The main problem of '-Og' is we must not use __attribute__((error(msg))).
> > The compiler will report error though the call to error function
> > still can be optimize out. So we must fallback to array tricky.
> I removed the sentence "So we must fallback to array tricky."
> Commit 81b45683487a51b0f4d3b29d37f20d6d078544e4
> killed the fallback to the negative array trick.
> I also resolved a conflict.
> Your series is now available in the following branch.
> git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild kbuild
> Please double check if I did it correctly.
I have tested your kbuild branch and no issues found. Thanks for checking this
> Best Regards
> Masahiro Yamada