Re: [PATCH 4/5] kernel hacking: new config DEBUG_EXPERIENCE to apply GCC -Og optimization

From: Randy Dunlap
Date: Tue May 01 2018 - 11:25:39 EST


Good morning.

On 05/01/2018 06:00 AM, changbin.du@xxxxxxxxx wrote:
> From: Changbin Du <changbin.du@xxxxxxxxx>
>
>
> Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
> ---
> Makefile | 4 ++++
> include/linux/compiler-gcc.h | 2 +-
> include/linux/compiler.h | 2 +-
> lib/Kconfig.debug | 21 +++++++++++++++++++++
> 4 files changed, 27 insertions(+), 2 deletions(-)
>

> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 90f35ad..2432e77d 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -211,6 +211,27 @@ config NO_AUTO_INLINE
>
> Use only if you want to debug the kernel.
>
> +config DEBUG_EXPERIENCE
> + bool "Optimize for better debugging experience (-Og)"
> + default n
> + select NO_AUTO_INLINE
> + depends on !CC_OPTIMIZE_FOR_SIZE
> + help
> + This will apply GCC '-Og' optimization level get supported from

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 perfer keeping

while preferring to keep

> + debug ability over runtime speed. The overall performance will
> + drop a bit.
> +
> + If enabling this option break your kernel, you should either

breaks

> + disable this or find a fix (mostly in the arch code). Currently
> + this option has only be tested in qemu x86_64 guest.
> +
> + Use only if you want to debug the kernel, especially if you want
> + to have better kernel debugging experience with gdb facilities
> + like kgdb and qemu.
> +
> config ENABLE_WARN_DEPRECATED
> bool "Enable __deprecated logic"
> default y
>

thanks,
--
~Randy