Re: [PATCHv3 2/3] kernel: add support for live patching

[Josh Poimboeuf]

On Fri, Nov 21, 2014 at 01:22:33AM +0100, Jiri Kosina wrote:
> On Thu, 20 Nov 2014, Seth Jennings wrote:
> > --- /dev/null
> > +++ b/kernel/livepatch/Kconfig
> > @@ -0,0 +1,18 @@
> > +config ARCH_HAVE_LIVE_PATCHING
> > +	boolean
> > +	help
> > +	  Arch supports kernel live patching
> > +
> > +config LIVE_PATCHING
> > +	boolean "Kernel Live Patching"
> > +	depends on DYNAMIC_FTRACE_WITH_REGS
> > +	depends on MODULES
> > +	depends on SYSFS
> > +	depends on KALLSYMS_ALL
> > +	depends on ARCH_HAVE_LIVE_PATCHING
> 
> We have to refuse to build on x86_64 if the compiler doesn't support 
> fentry. mcount is not really usable (well, it would be possible to use it, 
> be the obstacles are too big to care).
> 
> Something like [1] should be applicable here as well I believe.
> 
> [1] https://git.kernel.org/cgit/linux/kernel/git/jirislaby/kgraft.git/commit/?h=kgraft&id=bd4bc097c72937d18036f1312a4d79ed0bea9991

I think we can use "depends on HAVE_FENTRY" to accomplish this, since
CC_USING_FENTRY gets set by the top level kernel Makefile if
CONFIG_HAVE_FENTRY is set.

-- 
Josh
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