kernel-yocto: conditionally enable stack protection checking on x86-64
The kernel Makfile uses pkgconfig to check for libelf when enabling
CONFIG_STACK_VALIDATION. We already have libelf in our DEPENDS, but
the kernel Makefiles hardcode 'pkgconfig', so fail to pick up our
pkgconfig-native binary that would report the correct flags and paths
for libelf support.
Rather than patching the kernel Makefile's to use pkgconfig-native,
we can use the KERNEL_EXTRA_ARGS variable to pass the definition of
HOST_LIBELF_LIBS via the kernel build commmand line.
We conditionally set HOST_LIBELF_LIBS based on "stack" being in
a newly introduced variable KERNEL_DEBUG_OPTIONS. The value of
HOST_LIBELF_LIBS is the same as pkgconfig-native would set in a
kernel build (but we cannot call pkgconfig at the point this
variable is set).
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
