Messages in this thread |  | | Date | Fri, 26 Jul 2019 10:54:36 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v4 2/2] x86/purgatory: use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS |
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On Thu, 25 Jul 2019, Nick Desaulniers wrote:
> KBUILD_CFLAGS is very carefully built up in the top level Makefile, > particularly when cross compiling or using different build tools. > Resetting KBUILD_CFLAGS via := assignment is an antipattern. > > The comment above the reset mentions that -pg is problematic. Other > Makefiles use `CFLAGS_REMOVE_file.o = $(CC_FLAGS_FTRACE)` when > CONFIG_FUNCTION_TRACER is set. Prefer that pattern to wiping out all of > the important KBUILD_CFLAGS then manually having to re-add them. Seems > also that __stack_chk_fail references are generated when using > CONFIG_STACKPROTECTOR or CONFIG_STACKPROTECTOR_STRONG.
Looking at the resulting build flags. Most stuff looks correct but there are a few which need to be looked at twice.
removes:
-ffreestanding -fno-builtin -fno-zero-initialized-in-bss
changes:
-mcmodel=large to -mcmodel=kernel
adds:
-mindirect-branch-register -mindirect-branch=thunk-extern
The latter makes me nervous. That probably wants to have retpoline disabled as well. It's not having an instance right now, but ...
Thanks,
tglx
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