linux-kernel - Re: [PATCH 2/2] Add CONFIG_READABLE

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Date:	Tue, 8 May 2012 21:36:12 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Andi Kleen <ak@...ux.intel.com>, Andi Kleen <andi@...stfloor.org>,
	linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
	x86@...nel.org
Subject: Re: [PATCH 2/2] Add CONFIG_READABLE_ASM

On Thu, Apr 12, 2012 at 10:35 PM, Sam Ravnborg <sam@...nborg.org> wrote:
> On Thu, Apr 12, 2012 at 10:17:07PM +0200, Geert Uytterhoeven wrote:
>> On Thu, Apr 12, 2012 at 22:07, Sam Ravnborg <sam@...nborg.org> wrote:
>> > Could you try this:
>> >
>> > cc-disable-opt = $(call try-run,\
>> >        $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -f$(strip $(1)) -c -xc /dev/null -o "$TMP",-fno-$(strip $(1)))
>> >
>> > KBUILD_CFLAGS += $(call cc-disable-opt, ipa-cp-clone)
>> >
>> >
>> > It will try if "gcc -fipa-cp-clone" is supported,
>> > and add -fno-ipa-cp-clone in that case.
>>
>> Unfortunately not:
>>
>> m68k-linux-gnu-gcc -Wp,-MD,kernel/.bounds.s.d  -nostdinc -isystem
>> /usr/lib/gcc/m68k-linux-gnu/4.1.2/include
>> -I/scratch/geert/linux/linux-next/arch/m68k/include
>> Iarch/m68k/include/generated -Iinclude  -include
>> /scratch/geert/linux/linux-next/include/linux/kconfig.h -D__KERNEL__
>> -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing
>> -fno-common -Werror-implicit-function-declaration -Wno-format-security
>> -fno-delete-null-pointer-checks -Os -fno-reorder-blocks
>> -fno-ipa-cp-clone -pipe -fno-strength-reduce -ffixed-a2
>> -fno-omit-frame-pointer -fno-optimize-sibling-calls -g
>> -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(bounds)"
>> -D"KBUILD_MODNAME=KBUILD_STR(bounds)" -fverbose-asm -S -o
>> kernel/bounds.s kernel/bounds.c
>> cc1: error: unrecognized command line option "-fno-ipa-cp-clone"
>> make[1]: *** [kernel/bounds.s] Error 1
>> make: *** [prepare0] Error 2
>
> So with the above command-line gcc fails with an exit code for -fno-ipa-cp-clone.
> But with cc-option it does not.
>
> Can you dig out the command-line used for cc-option?
> We may be able to analyze why it fails in the above case, but
> not with cc-option.

gcc -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs
-fno-strict-aliasing -fno-common -Werror-implicit-function-declaration
-Wno-format-security -fno-delete-null-pointer-checks -Os
-fno-ipa-cp-clone -c -xc /dev/null -o .6376.tmp

So it's running "gcc" instead of "m68k-linux-gnu-gcc".

I used the gmail-damaged patch below to get the command in /tmp/x.

diff --git a/Makefile b/Makefile
index d17a616..0e0cbb9 100644
--- a/Makefile
+++ b/Makefile
@@ -567,7 +567,7 @@ ifdef CONFIG_READABLE_ASM
 # ipa clone creates specialized cloned functions
 # partial inlining inlines only parts of functions
 KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \
-                 $(call cc-option,-fno-ipa-cp-clone,) \
+                 $(call cc-option2,-fno-ipa-cp-clone,) \
                  $(call cc-option,-fno-partial-inlining)
 endif

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 6a3ee98..41c80bf 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -94,6 +94,16 @@ try-run = $(shell set -e;            \
        fi;                             \
        rm -f "$$TMP" "$$TMPO")

+try-run2 = $(shell set -e;             \
+       TMP="$(TMPOUT).$$$$.tmp";       \
+       TMPO="$(TMPOUT).$$$$.o";        \
+       echo "$(1)" > /tmp/x;           \
+       if ($(1)) >/dev/null 2>&1;      \
+       then echo "$(2)";               \
+       else echo "$(3)";               \
+       fi;                             \
+       rm -f "$$TMP" "$$TMPO")
+
 # as-option
 # Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)

@@ -112,6 +122,9 @@ as-instr = $(call try-run,\
 cc-option = $(call try-run,\
        $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc
/dev/null -o "$$TMP",$(1),$(2))

+cc-option2 = $(call try-run2,\
+       $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc
/dev/null -o "$$TMP",$(1),$(2))
+
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
 cc-option-yn = $(call try-run,\

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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