[linux-yocto] [yocto-kernel-cache][PATCH] features/systemtap/systemtap.cfg: enable CONFIG_KERNEL_DEBUG

[Bruce Ashfield]

As it turns out, Ross is reporting a big performance degradation in the kernel
in footprint, packaging and build time.

It completely slipped my mind when looking at this commit, that we went through
a split two years ago for that very same issue.

For now, I'm going to revert this, and then work systemtap properly into the
developer kernel type. The issue is that the standard kernel includes systemtap
by default (it probably shouldn't), and hence is picking up the DEBUG_KERNEL
option .. and that's causing the issues.

For now, you can build the developer kernel type, or add the developer kernel
configuration fragment via a bbappend, and you'll have a functional systemtap.

I can move systemtap out of the standard kernel and only into the developer
kernel, since as you say, it isn't functional without this option.
But, that ktype
hasn't gotten a lot of mileage (despite being around for two years),
so I'll need
to run some tests before I can truly move the fragment over and confirm that
it works.

So again, for now, I'll revert this, but will work on getting the
ktypes fixed up
as well.

Cheers,

Bruce


commit a7b57bb54cace686911faae9a8eace3b9cbf8145
Author: California Sullivan <california.l.sullivan at intel.com>
Date:   Wed Feb 17 16:47:10 2016 -0800

    ktypes: add developer ktype

    The developer ktype enables EMBEDDED, EXPERT, and DEBUG_KERNEL,
    opening up more kernel options and setting some defaults.

    Signed-off-by: California Sullivan <california.l.sullivan at intel.com>
    Signed-off-by: Bruce Ashfield <bruce.ashfield at windriver.com>

:000000 100644 000000000000... ee04ec720188... A
ktypes/developer/developer.cfg
:000000 100644 000000000000... cf2c0e6519d5... A
ktypes/developer/developer.scc



On Sat, Mar 3, 2018 at 9:03 PM, Victor Kamensky <kamensky at cisco.com> wrote:
> Need to enable CONFIG_KERNEL_DEBUG in systemtap feature, otherwise
> CONFIG_DEBUG_INFO set by systemtap.cfg does not have any effect since
> it depends on CONFIG_KERNEL_DEBUG and is set off in resulting config.
> So systemtap cannot find DWARF information in resulting kernel.
>
> Signed-off-by: Victor Kamensky <kamensky at cisco.com>
> ---
>  features/systemtap/systemtap.cfg | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/features/systemtap/systemtap.cfg b/features/systemtap/systemtap.cfg
> index acc2405..858447c 100644
> --- a/features/systemtap/systemtap.cfg
> +++ b/features/systemtap/systemtap.cfg
> @@ -1,4 +1,5 @@
>  CONFIG_RELAY=y
> +CONFIG_DEBUG_KERNEL=y
>  CONFIG_DEBUG_INFO=y
>  CONFIG_DEBUG_FS=y
>  CONFIG_MODULES=y
> --
> 2.7.4
>
> --
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"Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end"