On Mon, Aug 24, 2020 at 9:30 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > On Mon, 24 Aug 2020 10:59:13 +0800 > Nicolas Boichat <drinkcat@xxxxxxxxxxxx> wrote: > > > --- > > > > +ifeq ($(KBUILD_DISALLOW_TRACE_PRINTK),1) > > +KBUILD_CFLAGS += -DDISALLOW_TRACE_PRINTK > > +endif > > + > > KBUILD_CFLAGS += $(DEBUG_CFLAGS) > > export DEBUG_CFLAGS > > > > > There's one more thing we need to do, is if you build without this option > then build with it, you should trigger a full kernel rebuild. > Otherwise, if you build without the option, then build with it, and it > doesn't rebuild the tree, it wont catch anything. This already works. I'll be honest, I'm not 100% sure why (and if fully intentional)... The CFLAGS end up in 3 generated assembly files: # grep -R DISALLOW_TRACE_PRINTK * | grep -v ".cmd:" arch/x86/kernel/asm-offsets.s:# -imultiarch x86_64-linux-gnu -D __KERNEL__ -D DISALLOW_TRACE_PRINTK kernel/bounds.s:# -imultiarch x86_64-linux-gnu -D __KERNEL__ -D DISALLOW_TRACE_PRINTK scripts/mod/devicetable-offsets.s:# -D DISALLOW_TRACE_PRINTK (along with all *.cmd files) and I suspect some/all of those force a complete kernel rebuild. > -- Steve
