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SubjectRe: [PATCH] Makefile: Unset stack-protector gcc flag if it is not supported
On 02/20/2014 12:53 PM, Richard Weinberger wrote:
> On Thu, Feb 20, 2014 at 1:46 PM, Markos Chandras
> <Markos.Chandras@imgtec.com> wrote:
>> On 02/07/2014 05:15 PM, Markos Chandras wrote:
>>>
>>> In case the compiler does not support the stack-protector option,
>>> unset the flag to avoid build failures. Printing a warning is enough
>>> to let the user know that this flag will not be used.
>>> Fixes the following build problem when using a toolchain which does
>>> not support the -fstack-protector-strong flag:
>>>
>>> Makefile:614: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG:
>>> -fstack-protector-strong not supported by compiler
>>> mips-linux-gnu-gcc: error: unrecognized command line option
>>> '-fstack-protector-strong'
>>> scripts/Makefile.build:308: recipe for target 'scripts/mod/empty.o' failed
>>> make[2]: *** [scripts/mod/empty.o] Error 1
>>> make[2]: *** Waiting for unfinished jobs....
>>> scripts/Makefile.build:455: recipe for target 'scripts/mod' failed
>>>
>>> Cc: Michal Marek <mmarek@suse.cz>
>>> Cc: linux-kbuild@vger.kernel.org
>>> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
>>> ---
>>> Makefile | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/Makefile b/Makefile
>>> index 606ef7c..63a5333 100644
>>> --- a/Makefile
>>> +++ b/Makefile
>>> @@ -607,12 +607,14 @@ ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
>>> ifeq ($(call cc-option, $(stackp-flag)),)
>>> $(warning Cannot use CONFIG_CC_STACKPROTECTOR: \
>>> -fstack-protector not supported by compiler))
>>> + stackp-flag :=
>>> endif
>>> else ifdef CONFIG_CC_STACKPROTECTOR_STRONG
>>> stackp-flag := -fstack-protector-strong
>>> ifeq ($(call cc-option, $(stackp-flag)),)
>>> $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
>>> -fstack-protector-strong not supported by compiler)
>>> + stackp-flag :=
>>> endif
>>> else
>>> # Force off for distro compilers that enable stack protector by
>>> default.
>>>
>>
>> Ping again?
>
> This is by design. We want the build fail if
> CONFIG_CC_STACKPROTECTOR_STRONG is set
> but the toolchain does not support it.
> Otherwise we could end up with a kernel without stackprotector even if
> the config symbol is set.
>

Hi Richard,

Then maybe the $(warning...) should be converted to $(error...)?
Because it's not really a warning if the build failure is expected to
happen.

--
markos



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