[U-Boot-Users] [PATCH][ARM] Rationalize ARM compiler options
Peter Pearse
peter.pearse at arm.com
Mon Feb 18 15:50:39 CET 2008
Patch revised in light of list comments.
This patch completely replaces:-
"
Rationalize ARM compiler options
Date: 2008-02-13 15:55:00 GMT
"
---
Signed-off-by: Peter Pearse <peter.pearse at arm.com>
---
diff --git a/cpu/arm1136/config.mk b/cpu/arm1136/config.mk
index 6ab0dd3..cf47130 100644
--- a/cpu/arm1136/config.mk
+++ b/cpu/arm1136/config.mk
@@ -20,16 +20,15 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-# Make ARMv5 to allow more compilers to work, even though its v6.
-PLATFORM_CPPFLAGS += -march=armv5
# =========================================================================
-#
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+PLATFORM_CPPFLAGS += -march=armv6
+# =========================================================================
# Supply options according to compiler version
-#
# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_CPPFLAGS +=$(call cc-option,-mno-thumb-interwork,)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
+
diff --git a/cpu/arm720t/config.mk b/cpu/arm720t/config.mk
index 641b91c..378751c 100644
--- a/cpu/arm720t/config.mk
+++ b/cpu/arm720t/config.mk
@@ -21,15 +21,15 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-PLATFORM_CPPFLAGS += -march=armv4 -mtune=arm7tdmi
# =========================================================================
-#
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+PLATFORM_CPPFLAGS += -march=armv4t
+# =========================================================================
# Supply options according to compiler version
-#
# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
+
diff --git a/cpu/arm920t/config.mk b/cpu/arm920t/config.mk
index 8db4adb..7ecf8c3 100644
--- a/cpu/arm920t/config.mk
+++ b/cpu/arm920t/config.mk
@@ -20,15 +20,15 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-PLATFORM_CPPFLAGS += -march=armv4
# =========================================================================
-#
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+PLATFORM_CPPFLAGS += -march=armv4t
+# =========================================================================
# Supply options according to compiler version
-#
# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
+
diff --git a/cpu/arm925t/config.mk b/cpu/arm925t/config.mk
index 8db4adb..7ecf8c3 100644
--- a/cpu/arm925t/config.mk
+++ b/cpu/arm925t/config.mk
@@ -20,15 +20,15 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-PLATFORM_CPPFLAGS += -march=armv4
# =========================================================================
-#
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+PLATFORM_CPPFLAGS += -march=armv4t
+# =========================================================================
# Supply options according to compiler version
-#
# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
+
diff --git a/cpu/arm926ejs/config.mk b/cpu/arm926ejs/config.mk
index 8db4adb..88182bc 100644
--- a/cpu/arm926ejs/config.mk
+++ b/cpu/arm926ejs/config.mk
@@ -20,15 +20,15 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-PLATFORM_CPPFLAGS += -march=armv4
# =========================================================================
-#
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+PLATFORM_CPPFLAGS += -march=armv5te
+# =========================================================================
# Supply options according to compiler version
-#
# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
+
diff --git a/cpu/arm946es/config.mk b/cpu/arm946es/config.mk
index 81ca288..88182bc 100644
--- a/cpu/arm946es/config.mk
+++ b/cpu/arm946es/config.mk
@@ -20,8 +20,15 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
+# =========================================================================
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+PLATFORM_CPPFLAGS += -march=armv5te
+# =========================================================================
+# Supply options according to compiler version
+# =========================================================================
+PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-PLATFORM_CPPFLAGS += -march=armv4
diff --git a/cpu/arm_intcm/config.mk b/cpu/arm_intcm/config.mk
index 81ca288..954f366 100644
--- a/cpu/arm_intcm/config.mk
+++ b/cpu/arm_intcm/config.mk
@@ -20,8 +20,16 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
+# =========================================================================
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+# This cpu intended for unknown cpu - use lowest common architecture
+PLATFORM_CPPFLAGS += -march=armv4
+# =========================================================================
+# Supply options according to compiler version
+# =========================================================================
+PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-PLATFORM_CPPFLAGS += -march=armv4
diff --git a/cpu/ixp/config.mk b/cpu/ixp/config.mk
index a71a20b..f18113a 100644
--- a/cpu/ixp/config.mk
+++ b/cpu/ixp/config.mk
@@ -21,17 +21,18 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-BIG_ENDIAN = y
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float -mbig-endian
-
+# =========================================================================
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float \
+ -mbig-endian
PLATFORM_CPPFLAGS += -mbig-endian -march=armv5te -mtune=strongarm1100
# =========================================================================
-#
# Supply options according to compiler version
-#
# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
+BIG_ENDIAN = y
+
+
diff --git a/cpu/lh7a40x/config.mk b/cpu/lh7a40x/config.mk
index 10e755b..58269f0 100644
--- a/cpu/lh7a40x/config.mk
+++ b/cpu/lh7a40x/config.mk
@@ -20,15 +20,14 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
+# =========================================================================
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
PLATFORM_CPPFLAGS += -march=armv4
# =========================================================================
-#
# Supply options according to compiler version
-#
-# ========================================================================
+# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
diff --git a/cpu/pxa/config.mk b/cpu/pxa/config.mk
index f0b86b7..3cb4b16 100644
--- a/cpu/pxa/config.mk
+++ b/cpu/pxa/config.mk
@@ -21,15 +21,14 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
+# =========================================================================
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
PLATFORM_CPPFLAGS += -march=armv5te -mtune=xscale
# =========================================================================
-#
# Supply options according to compiler version
-#
-# ========================================================================
+# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
diff --git a/cpu/s3c44b0/config.mk b/cpu/s3c44b0/config.mk
index 6dc9c46..4dfd17c 100644
--- a/cpu/s3c44b0/config.mk
+++ b/cpu/s3c44b0/config.mk
@@ -21,15 +21,14 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
-PLATFORM_CPPFLAGS += -march=armv4 -mtune=arm7tdmi -msoft-float
# =========================================================================
-#
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
+PLATFORM_CPPFLAGS += -march=armv4 -mtune=arm7tdmi
+# =========================================================================
# Supply options according to compiler version
-#
-# ========================================================================
+# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
diff --git a/cpu/sa1100/config.mk b/cpu/sa1100/config.mk
index 5be7dfb..67d3b26 100644
--- a/cpu/sa1100/config.mk
+++ b/cpu/sa1100/config.mk
@@ -21,15 +21,14 @@
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
-
-PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 \
- -msoft-float
-
+# =========================================================================
+# See doc/README.ARM.config.mk for a justification of the ARM specific
options
+# =========================================================================
+PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8
-msoft-float
PLATFORM_CPPFLAGS += -march=armv4 -mtune=strongarm1100
# =========================================================================
-#
# Supply options according to compiler version
-#
-# ========================================================================
+# =========================================================================
PLATFORM_CPPFLAGS +=$(call cc-option,-mapcs-32,-mabi=apcs-gnu)
-PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call
cc-option,-malignment-traps,))
+PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,))
+PLATFORM_RELFLAGS +=$(call cc-option,-malignment-traps,))
diff --git a/doc/README.ARM.config.mk b/doc/README.ARM.config.mk
new file mode 100644
index 0000000..016cd1d
--- /dev/null
+++ b/doc/README.ARM.config.mk
@@ -0,0 +1,75 @@
+The GNU compiler ARM specific options in the ARM cpu directory config.mk
files
+are intended to be general enough to apply for all boards with those cpus,
+when compiled with the latest ELDK arm toolchains.
+Individual boards and/or blocks of code may have their performance and/or
+memory footprint improved by using more particular combinations of options
+and/or toolchains. Such changes can be applied in the relevant cpu
config.mk.
+You are encouraged to submit evidence of such improvements to
+u-boot-users at lists.sourceforge.net. However, it is unlikely that such
+individual settings will be incorporated into the main code-tree.
+This file might provide a good place to document them
+- see "Board and/or toolchain specific optimizations" below.
+---------------------------------------------------------------------------
---
+The make function cc-option imported from the linux kernel to
u-boot/config.mk
+is used to
+a) check whether a particular option is supported by the toolchain
+b) provide an alternative to unsupported options, where applicable.
+---------------------------------------------------------------------------
---
+-march indicates the architecture implemented by the processor core.
+---------------------------------------------------------------------------
---
+The gcc-3.4.6 manual has:-
+-mapcs-32
+ Generate code for a processor running with a 32-bit program counter,
+ and conforming to the function calling standards for the APCS
+ 32-bit option.
+ This flag is deprecated.
+ Future releases of GCC will make this flag unconditional.
+-malignment-traps
+ Generate code that will not trap if the MMU has alignment traps
+ enabled. On ARM architectures prior to ARMv4, there were no
+ instructions to access half-word objects stored in memory. However,
+ when reading from memory a feature of the ARM architecture allows a
+ word load to be used, even if the address is unaligned, and the
+ processor core will rotate the data as it is being loaded.
+ This option tells the compiler that such misaligned accesses will
cause
+ a MMU trap and that it should instead synthesize the access as a
series
+ of byte accesses. The compiler can still use word accesses to load
+ half-word data if it knows that the address is aligned to a word
+ boundary.
+ This option has no effect when compiling for ARM architecture 4 or
+ later, since these processors have instructions to directly access
+ half-word objects in memory.
+ -mshort-load-bytes
+---------------------------------------------------------------------------
---
+The gcc-2.9.53 manual has:-
+-mshort-load-bytes
+ Do not try to load half-words (eg `short's) by loading a word from
an
+ unaligned address. For some targets the MMU is configured to trap
+ unaligned loads; use this option to generate code that is safe in
+ these environments.
+---------------------------------------------------------------------------
---
+Floating point code will not be accepted into the U-Boot main tree.
+However, the ELDK toolchains provide floating point support and are built
+with the -msoft-float option. Hence, this option is supplied to the U-Boot
code
+to ensure any floating point arithmetic, included locally, links in the
floating
+point support code correctly.
+---------------------------------------------------------------------------
---
+Please note:-
+a) U-Boot is intended to be statically linked binary.
+ Hence toolchains which make linux kernel calls e.g. to raise()
should
+ not be used.
+b) -ffixed-r8 will not allow access to the gd pointer in ARM FIQ mode
+ since FIQ mode has it's own r8.
+ A patch to use another shared register is planned by
+ peter.pearse<at>arm.com.
+c) Information regarding the Code Sourcery EABI toolchains is available
+ from http://www.codesourcery.com.
+ See esp. http://www.codesourcery.com/archives.
+d) If using a toolchain which has not been built to offer ARM/thumb
+ interworking the following line, added to config.mk will remove
+ warnings of the form "X does not support interworking, whereas Y
does"
+ PLATFORM_CPPFLAGS +=$(call cc-option,-mno-thumb-interwork,)
+---------------------------------------------------------------------------
---
+Board and/or toolchain specific optimizations
+=============================================
+TBD
--
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