2mo ago

I cannot enable `HAVE_KPROBES_ON_FTRACE` - Kernel compile

Hi,

I have a great piece of software, that apparently need HAVE_KPROBES_ON_FTRACE

To config the kernel option I'm using :

 shell

    
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- menuconfig

The Kernel is Linux/arm64 6.6.63

When I'm doing a search inside menuconfig i get:

 shell

    
Symbol: HAVE_KPROBES_ON_FTRACE [=n]
Type  : bool
Defined at arch/Kconfig:223


Symbol: KPROBES_ON_FTRACE [=n]
Type  : bool
Defined at arch/Kconfig:117
 Depends on: KPROBES [=y] && HAVE_KPROBES_ON_FTRACE [=n] && DYNAMIC_FTRACE_WITH_REGS [=n]

But I found it no where in the menu... and if I add it mannuly in the .config file, then make some more other adapations in menuconfig my manual entry disappear..

Any ideas ?

Maybe HAVE_KPROBES_ON_FTRACE is not supported in 6.6.63 ?

Thanks

6 comments

The options that start with HAVE_ usually depend on the arch or compiler. I don't believe it's possible to enable manually without modifying the source itself.
- Thanks @SteveTech@programming.dev
  I suppose the file linux/arch/Kconfig is the base the menuconfig to know which option is available ? right ?
  Thanks.
  
  Yes, but it doesn't look like KPROBES_ON_FTRACE is supported on arm64. I did find this patch though which implements it: https://patchwork.kernel.org/project/linux-arm-kernel/patch/20191218140622.57bbaca5@xhacker.debian/
  If you don't know how to apply a patch, you can either paste the link into b4, or download the mbox and apply it with git am.

It's possible that it's not supported on your arch.
- Thanks, how can we verify this ?
  
  Basically just start with what you're aiming to enable and work backwards (as you've started to do). With judicious use of grep find out where that symbol is defined. If it's in arch configs for other arches but not your own, it's probably that.
  There may be better tools out there to do this, but in my experience just sleuthing it out a bit will answer your question. The Kconfig system can be complex, but the files are pretty readable.

6 comments