lkml.org 
[lkml]   [2012]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[tip:x86/cleanups] debug: Add CONFIG_READABLE_ASM
    Commit-ID:  1873e870fd63ee4b87dbe0125ca373e420fb4987
    Gitweb: http://git.kernel.org/tip/1873e870fd63ee4b87dbe0125ca373e420fb4987
    Author: Andi Kleen <ak@linux.intel.com>
    AuthorDate: Wed, 28 Mar 2012 11:51:18 -0700
    Committer: H. Peter Anvin <hpa@zytor.com>
    CommitDate: Fri, 30 Mar 2012 10:15:21 -0700

    debug: Add CONFIG_READABLE_ASM

    Add a config option to disable various gcc compiler optimizations that
    make assembler listings much harder to read. This is everything that reorders
    code significantly or creates partial functions.

    This is mainly to keep kernel hackers sane.

    Signed-off-by: Andi Kleen <ak@linux.intel.com>
    Link: http://lkml.kernel.org/r/1332960678-11879-2-git-send-email-andi@firstfloor.org
    Signed-off-by: H. Peter Anvin <hpa@zytor.com>
    ---
    Makefile | 10 ++++++++++
    lib/Kconfig.debug | 9 +++++++++
    2 files changed, 19 insertions(+), 0 deletions(-)

    diff --git a/Makefile b/Makefile
    index 1932984..6f7328b 100644
    --- a/Makefile
    +++ b/Makefile
    @@ -564,6 +564,16 @@ else
    KBUILD_CFLAGS += -O2
    endif

    +ifdef CONFIG_READABLE_ASM
    +# Disable optimizations that make assembler listings hard to read.
    +# reorder blocks reorders the control in the function
    +# 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-option,-fno-partial-inlining)
    +endif
    +
    include $(srctree)/arch/$(SRCARCH)/Makefile

    ifneq ($(CONFIG_FRAME_WARN),0)
    diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
    index 6777153..4d3cbbb 100644
    --- a/lib/Kconfig.debug
    +++ b/lib/Kconfig.debug
    @@ -70,6 +70,15 @@ config STRIP_ASM_SYMS
    that look like '.Lxxx') so they don't pollute the output of
    get_wchan() and suchlike.

    +config READABLE_ASM
    + bool "Generate readable assembler code"
    + depends on DEBUG_KERNEL
    + help
    + Disable some compiler optimizations that tend to generate human unreadable
    + assembler output. This may make the kernel slightly slower, but it helps
    + to keep kernel developers who have to stare a lot at assembler listings
    + sane.
    +
    config UNUSED_SYMBOLS
    bool "Enable unused/obsolete exported symbols"
    default y if X86

    \
     
     \ /
      Last update: 2012-03-30 19:43    [W:0.023 / U:60.464 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site