From: mail@xxxxxxxxxx <mail@xxxxxxxxxx>
This patch gives ability for add some "-fno-..." options for GCC
and to force -O1 optimization. Supporting files, like Kconfig, Makefile
are auto-generated due to large amount of available options.
Patch helps to debug kernel.
---
Makefile | 11 ++++
lib/Kconfig.debug | 2 +
lib/Kconfig.debug.optim | 102 ++++++++++++++++++++++++++++++++++++
scripts/Makefile.optim.inc | 23 ++++++++
scripts/debug/make_config_optim.sh | 88 +++++++++++++++++++++++++++++++
5 files changed, 226 insertions(+), 0 deletions(-)
create mode 100644 lib/Kconfig.debug.optim
create mode 100644 scripts/Makefile.optim.inc
create mode 100644 scripts/debug/make_config_optim.sh
diff --git a/Makefile b/Makefile
index 7c44b67..bc9a961 100644
--- a/Makefile
+++ b/Makefile
@@ -558,12 +558,23 @@ endif # $(dot-config)
# Defaults to vmlinux, but the arch makefile usually adds further targets
all: vmlinux
+ifdef CONFIG_HACK_OPTIM_FORCE_O1_LEVEL
+KBUILD_CFLAGS += -O1
+else
+
ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS += -Os
else
KBUILD_CFLAGS += -O2
endif
+endif
+
+# Include makefile for optimization override
+ifdef CONFIG_HACK_OPTIM
+include $(srctree)/scripts/Makefile.optim.inc
+endif
+
include $(srctree)/arch/$(SRCARCH)/Makefile
ifneq ($(CONFIG_FRAME_WARN),0)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8745ac7..928265e 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1274,5 +1274,7 @@ source "lib/Kconfig.kgdb"
source "lib/Kconfig.kmemcheck"
+source "lib/Kconfig.debug.optim"
+
config TEST_KSTRTOX
tristate "Test kstrto*() family of functions at runtime"
diff --git a/lib/Kconfig.debug.optim b/lib/Kconfig.debug.optim
new file mode 100644
index 0000000..09b1012
--- /dev/null
+++ b/lib/Kconfig.debug.optim
@@ -0,0 +1,102 @@
+# This file was auto generated. It's utility configuration
+# Distributed under GPL v2 License
+
+menuconfig HACK_OPTIM
+ bool "Allows to override GCC optimization"
+ depends on DEBUG_KERNEL && EXPERIMENTAL
+ help
+ If you say Y here you will be able to override
+ how GCC optimize kernel code. This will create
+ more debug friendly, but with not guarentee
+ about same runi, like production, kernel.
+
+ If you say Y here probably You will want say
+ for all suboptions
+
+if HACK_OPTIM
+
+config HACK_OPTIM_FORCE_O1_LEVEL
+ bool "Forces -O1 optimization level"
+ ---help---
+ This will change how GCC optimize code. Code
+ may be slower and larger but will be more debug
+ "friendly".
+
+ In some cases there is low chance that kernel
+ will run different then normal, reporting or not
+ some bugs or errors. Refere to GCC manual for
+ more details.
+
+ You SHOULD say N here.
+
+config HACK_OPTIM__fno_inline_functions_called_once
+ bool "Adds -fno-inline-functions-called-once parameter to gcc invoke line."
+ ---help---
+ This will change how GCC optimize code. Code
+ may be slower and larger but will be more debug
+ "friendly".
+
+ In some cases there is low chance that kernel
+ will run different then normal, reporting or not
+ some bugs or errors. Refere to GCC manual for
+ more details.
+
+ You SHOULD say N here.
+
+config HACK_OPTIM__fno_combine_stack_adjustments
+ bool "Adds -fno-combine-stack-adjustments parameter to gcc invoke line."
+ ---help---
+ This will change how GCC optimize code. Code
+ may be slower and larger but will be more debug
+ "friendly".
+
+ In some cases there is low chance that kernel
+ will run different then normal, reporting or not
+ some bugs or errors. Refere to GCC manual for
+ more details.
+
+ You SHOULD say N here.
+
+config HACK_OPTIM__fno_tree_dce
+ bool "Adds -fno-tree-dce parameter to gcc invoke line."
+ ---help---
+ This will change how GCC optimize code. Code
+ may be slower and larger but will be more debug
+ "friendly".
+
+ In some cases there is low chance that kernel
+ will run different then normal, reporting or not
+ some bugs or errors. Refere to GCC manual for
+ more details.
+
+ You SHOULD say N here.
+
+config HACK_OPTIM__fno_tree_dominator_opts
+ bool "Adds -fno-tree-dominator-opts parameter to gcc invoke line."
+ ---help---
+ This will change how GCC optimize code. Code
+ may be slower and larger but will be more debug
+ "friendly".
+
+ In some cases there is low chance that kernel
+ will run different then normal, reporting or not
+ some bugs or errors. Refere to GCC manual for
+ more details.
+
+ You SHOULD say N here.
+
+config HACK_OPTIM__fno_dse
+ bool "Adds -fno-dse parameter to gcc invoke line."
+ ---help---
+ This will change how GCC optimize code. Code
+ may be slower and larger but will be more debug
+ "friendly".
+
+ In some cases there is low chance that kernel
+ will run different then normal, reporting or not
+ some bugs or errors. Refere to GCC manual for
+ more details.
+
+ You SHOULD say N here.
+
+endif #HACK_OPTIM
diff --git a/scripts/Makefile.optim.inc b/scripts/Makefile.optim.inc
new file mode 100644
index 0000000..e78cc92
--- /dev/null
+++ b/scripts/Makefile.optim.inc
@@ -0,0 +1,23 @@
+# This file was auto generated. It's utility configuration
+# Distributed under GPL v2 License
+
+ifdef CONFIG_HACK_OPTIM__fno_inline_functions_called_once
+ KBUILD_CFLAGS += -fno-inline-functions-called-once
+endif
+
+ifdef CONFIG_HACK_OPTIM__fno_combine_stack_adjustments
+ KBUILD_CFLAGS += -fno-combine-stack-adjustments
+endif
+
+ifdef CONFIG_HACK_OPTIM__fno_tree_dce
+ KBUILD_CFLAGS += -fno-tree-dce
+endif
+
+ifdef CONFIG_HACK_OPTIM__fno_tree_dominator_opts
+ KBUILD_CFLAGS += -fno-tree-dominator-opts
+endif
+
+ifdef CONFIG_HACK_OPTIM__fno_dse
+ KBUILD_CFLAGS += -fno-dse
+endif
+
diff --git a/scripts/debug/make_config_optim.sh b/scripts/debug/make_config_optim.sh
new file mode 100644
index 0000000..26865923
--- /dev/null
+++ b/scripts/debug/make_config_optim.sh
@@ -0,0 +1,88 @@
+#!/bin/sh
+
+## Utility script for generating optimization override options
+## for kernel compilation.
+##
+## Distributed under GPL v2 license
+## (c) Radosław Smogura, 2011
+
+# Prefix added for variable
+CFG_PREFIX="HACK_OPTIM"
+
+KCFG="Kconfig.debug.optim"
+MKFI="Makefile.optim.inc"
+
+OPTIMIZATIONS_PARAMS="-fno-inline-functions-called-once \
+ -fno-combine-stack-adjustments \
+ -fno-tree-dce \
+ -fno-tree-dominator-opts \
+ -fno-dse "
+
+echo "# This file was auto generated. It's utility configuration" > $KCFG
+echo "# Distributed under GPL v2 License" >> $KCFG
+echo >> $KCFG
+echo "menuconfig ${CFG_PREFIX}" >> $KCFG
+echo -e "\tbool \"Allows to override GCC optimization\"" >> $KCFG
+echo -e "\tdepends on DEBUG_KERNEL && EXPERIMENTAL" >> $KCFG
+echo -e "\thelp" >> $KCFG
+echo -e "\t If you say Y here you will be able to override" >> $KCFG
+echo -e "\t how GCC optimize kernel code. This will create" >> $KCFG
+echo -e "\t more debug friendly, but with not guarentee" >> $KCFG
+echo -e "\t about same runi, like production, kernel." >> $KCFG
+echo >> $KCFG
+echo -e "\t If you say Y here probably You will want say" >> $KCFG
+echo -e "\t for all suboptions" >> $KCFG
+echo >> $KCFG
+echo "if ${CFG_PREFIX}" >> $KCFG
+echo >> $KCFG
+
+echo "# This file was auto generated. It's utility configuration" > $MKFI
+echo "# Distributed under GPL v2 License" >> $MKFI
+echo >> $MKFI
+
+# Insert standard override optimization level
+# This is exception, and this value will not be included
+# in auto generated makefile. Support for this value
+# is hard coded in main Makefile.
+echo -e "config ${CFG_PREFIX}_FORCE_O1_LEVEL" >> $KCFG
+echo -e "\tbool \"Forces -O1 optimization level\"" >> $KCFG
+echo -e "\t---help---" >> $KCFG
+echo -e "\t This will change how GCC optimize code. Code" >> $KCFG
+echo -e "\t may be slower and larger but will be more debug" >> $KCFG
+echo -e "\t \"friendly\"." >> $KCFG
+echo >> $KCFG
+echo -e "\t In some cases there is low chance that kernel" >> $KCFG
+echo -e "\t will run different then normal, reporting or not" >> $KCFG
+echo -e "\t some bugs or errors. Refere to GCC manual for" >> $KCFG
+echo -e "\t more details." >> $KCFG
+echo >> $KCFG
+echo -e "\t You SHOULD say N here." >> $KCFG
+echo >> $KCFG
+
+for o in $OPTIMIZATIONS_PARAMS ; do
+ cfg_o="${CFG_PREFIX}_${o//-/_}";
+ echo "Processing param ${o} config variable will be $cfg_o";
+
+ # Generate kconfig entry
+ echo -e "config ${cfg_o}" >> $KCFG
+ echo -e "\tbool \"Adds $o parameter to gcc invoke line.\"" >> $KCFG
+ echo -e "\t---help---" >> $KCFG
+ echo -e "\t This will change how GCC optimize code. Code" >> $KCFG
+ echo -e "\t may be slower and larger but will be more debug" >> $KCFG
+ echo -e "\t \"friendly\"." >> $KCFG
+ echo >> $KCFG
+ echo -e "\t In some cases there is low chance that kernel" >> $KCFG
+ echo -e "\t will run different then normal, reporting or not" >> $KCFG
+ echo -e "\t some bugs or errors. Refere to GCC manual for" >> $KCFG
+ echo -e "\t more details." >> $KCFG
+ echo >> $KCFG
+ echo -e "\t You SHOULD say N here." >> $KCFG
+ echo >> $KCFG
+
+ #Generate Make for include
+ echo "ifdef CONFIG_${cfg_o}" >> $MKFI
+ echo -e "\tKBUILD_CFLAGS += $o" >> $MKFI
+ echo "endif" >> $MKFI
+ echo >> $MKFI
+done;
+echo "endif #${CFG_PREFIX}" >> $KCFG
--
1.7.3.4
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