Re: [PATCH 2/2] btf: Add the option to include global variable types

[Alexei Starovoitov]

On Thu, Feb 6, 2025 at 5:21 PM Stephen Brennan
<stephen.s.brennan@xxxxxxxxxx> wrote:
> When the feature was implemented in pahole, my measurements indicated
> that vmlinux BTF size increased by about 25.8%, and module BTF size
> increased by 53.2%. Due to these increases, the feature is implemented
> behind a new config option, allowing users sensitive to increased memory
> usage to disable it.
>

...
> +config DEBUG_INFO_BTF_GLOBAL_VARS
> +       bool "Generate BTF type information for all global variables"
> +       default y
> +       depends on DEBUG_INFO_BTF && PAHOLE_VERSION >= 128
> +       help
> +         Include type information for all global variables in the BTF. This
> +         increases the size of the BTF information, which increases memory
> +         usage at runtime. With global variable types available, runtime
> +         debugging and tracers may be able to provide more detail.

This is not a solution.
Even if it's changed to 'default n' distros will enable it
like they enable everything and will suffer a regression.

We need to add a new module like vmlinux_btf.ko that will contain
this additional BTF data. For global vars and everything else we might need.

pw-bot: cr