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Commit: MSP430: Add support for low & high sections
- From: Nick Clifton <nickc at redhat dot com>
- To: newlib at sourceware dot org
- Date: Tue, 05 May 2015 12:44:33 +0100
- Subject: Commit: MSP430: Add support for low & high sections
- Authentication-results: sourceware.org; auth=none
Hi Guys,
This patch supports an about-to-be-contributed patch to GCC for the
MSP430 will add the ability for the compiler and linker to dynamically
allocate data and code to either a low (<64K) memory region or a high
memory region. In order for this feature to work the MSP430 linker
scripts in libgloss need to be updated to handle some new sections.
In addition the linker scripts and startup code need to handle data
that is stored in (high memory) flash RAM and which needs to be
reinitialised when the processor is reset.
The patch also tidies up the libgloss/msp430 directory, removing a few
unneeded files.
Cheers
Nick
libgloss/ChangeLog
2015-05-05 Nick Clifton <nickc@redhat.com>
* msp430/msp430.ld: Delete.
* msp430/msp430F5438A-l.ld: Delete.
* msp430/msp430F5438A-s.ld: Delete.
* msp430/crt_movedata.S: Delete.
* msp430/Makefile.in (SCRIPTS): Remove msp430.ld.
(CRT_OBJS): Add crt_move_highdata.o.
* msp430/memmodel.h (START_CRT_FUNC): New macro.
(END_CRT_FUNC): New macro.
(WEAK_DEF): New macro.
* msp430/crt0.S: Use new macros.
(moev_highdata): New code to initialise the .data section if it is
held in high memory.
* msp430/msp430-sim.ld (.data): Add .either.data.
(.rodata2): Move some read-only data sections here.
(.text): Add .either.text.
(.rodata): Add .either.rodata.
(.bss): Add .either.bss.
* msp430/msp430xl-sim.ld (MEMORY): Add HIROM.
(.rodata2): Move some read-only data sections here.
(.upper.data): New section. Include notes about how to initialise
it.
diff --git a/libgloss/msp430/Makefile.in b/libgloss/msp430/Makefile.in
index 286cd89..fdd1513 100644
--- a/libgloss/msp430/Makefile.in
+++ b/libgloss/msp430/Makefile.in
@@ -57,8 +57,7 @@ OBJCOPY = `if [ -f ${objroot}/../binutils/objcopy ] ; \
then echo ${objroot}/../binutils/objcopy ; \
else t='$(program_transform_name)'; echo objcopy | sed -e $$t ; fi`
-SCRIPTS = $(srcdir)/msp430.ld
-SCRIPTS += $(srcdir)/msp430-sim.ld
+SCRIPTS = $(srcdir)/msp430-sim.ld
SCRIPTS += $(srcdir)/msp430xl-sim.ld
SCRIPTS += $(srcdir)/intr_vectors.ld
@@ -84,6 +83,7 @@ CRT_OBJS = \
crt_bss.o \
crt_high_bss.o \
crt_movedata.o \
+ crt_move_highdata.o \
crt_main.o \
crt_main_minrt.o \
crt_callexit.o \
diff --git a/libgloss/msp430/crt0.S b/libgloss/msp430/crt0.S
index c511959..375d476 100644
--- a/libgloss/msp430/crt0.S
+++ b/libgloss/msp430/crt0.S
@@ -1,4 +1,4 @@
-/* Copyright (c) 2012-2013 Red Hat, Inc. All rights reserved.
+/* Copyright (c) 2012-2015 Red Hat, Inc. All rights reserved.
This copyrighted material is made available to anyone wishing to use, modify,
copy, or redistribute it subject to the terms and conditions of the BSD
@@ -14,37 +14,64 @@
#include "memmodel.h"
;; The linker links all .crt_* sections in asciibetical order at the
-;; same place. So, the four digits in .crt_NNNN determine the link
-;; order, so, keep them in sequential order here. The first two
-;; digits are set here, the second two allow users to insert code
-;; between code fragments here.
+;; same place. So, the four digits in .crt_NNNN_xxx name created by
+;; the START_CRT_FUNC macro determine the link order, so, keep them
+;; in sequential order here. The first two digits are set here, the
+;; second two allow users to insert code between code fragments here.
#if L0
.section ".resetvec", "a"
__msp430_resetvec_hook:
- .word __start
+ .word __crt0_start
- .section ".crt_0000init", "ax", @progbits
+ ;; Here we provide weak definitions of the symbols used in the
+ ;; init_highbss and move_highdata blocks, in case they are not
+ ;; provided by the linker script. They are defined here because
+ ;; this block is always included in every executable, and because
+ ;; if there were defined in the blocks that need them their values
+ ;; would be used without giving the linker script a chance to
+ ;; override them.
+ ;;
+ ;; The weak definitions are needed if the user targets an MCU
+ ;; without high memory - and hence uses a linker script without
+ ;; a definition of the .upper.bss or .upper.data sections - and
+ ;; they have compiled their code with the -mdata-region=either
+ ;; command line option. That option causes the assembler to
+ ;; define the __crt0_move_highdata and/or crt0_init_highbss
+ ;; symbols, which in turn forces the inclusion of the
+ ;; move_highdata and/or init_highbss blocks in the startup code,
+ ;; regardless of the fact that the sections are not present in
+ ;; the linker script.
+
+ WEAK_DEF __upper_data_init
+ WEAK_DEF __rom_highdatacopysize
+ WEAK_DEF __high_datastart
+ WEAK_DEF __rom_highdatastart
+ WEAK_DEF __high_bssstart
+ WEAK_DEF __high_bsssize
+
+START_CRT_FUNC 0000 start
.refsym __msp430_resetvec_hook
#ifdef MINRT
.refsym __crt0_call_just_main
#else
.refsym __crt0_call_init_then_main
#endif
- .global __start
-__start:
mov_ #__stack, R1
;; Disable watchdog timer.
MOV #0x5a80, &0x15C
+END_CRT_FUNC start
#endif
+
#if Lbss
- .section ".crt_0100bss", "ax", @progbits
+;; Note - this section is only included in the startup code of the
+;; application if it is needed. It is responsible for initializing
+;; the contents of the .bss section.
+
+START_CRT_FUNC 0100 init_bss
- .global __crt0_init_bss
-__crt0_init_bss:
-
mov_ #__bssstart, R12
clr.w R13
mov.w #__bsssize, R14
@@ -52,32 +79,41 @@ __crt0_init_bss:
clr.w R15 ; We assume that __bsssize is never > 64M
#endif
call_ #memset
-#endif
+
+END_CRT_FUNC init_bss
+#endif /* Lbss */
+
#ifdef __MSP430X_LARGE__
#if Lhigh_bss
-;; Note - this section is only included in the
-;; startup code of the application if it is needed.
+;; Note - this section is only included in the startup code of the
+;; application if it is needed. It is responsible for initializing
+;; the contents of the .upper.bss section.
- .section ".crt_0150high_bss", "ax", @progbits
-
- .global __crt0_init_high_bss
-__crt0_init_high_bss:
+START_CRT_FUNC 0200 init_highbss
- mov_ #llo(__high_bssstart), R12
- mov_ #lhi(__high_bssstart), R13
- mov.w #llo(__high_bsssize), R14
- mov.w #lhi(__high_bsssize), R15
+ mov_ #__high_bssstart, R12
+ mov.w #0, R13
+ mov_ #__high_bsssize, R14
+ ;; If __high_bsssize is zero then skip the call to memset.
+ ;; This can happen if all of the bss data was placed into .either.bss.
+ cmp.w #0, R14
+ jeq 1f
call_ #memset
+1:
+END_CRT_FUNC init_highbss
#endif /* Lhigh_bss */
#endif /* __MSP430X_LARGE__ */
+
#if Lmovedata
- .section ".crt_0200movedata", "ax", @progbits
+;; Note - this section is only included in the startup code of the
+;; application if it is needed. It is responsible for copying the
+;; contents of the .data section from its load address (in ROM) to
+;; its run-time address (in RAM).
+
+START_CRT_FUNC 0300 movedata
- .global __crt0_movedata
-__crt0_movedata:
-
mov_ #__datastart, R12
mov_ #__romdatastart, R13
@@ -85,44 +121,104 @@ __crt0_movedata:
cmp_ R12, R13
jeq 1f
- mov.w #__romdatacopysize, R14
+ mov_ #__romdatacopysize, R14
+
+ call_ #memmove
+1:
+END_CRT_FUNC movedata
+#endif /* Lmovedata */
+
+
#ifdef __MSP430X_LARGE__
- clr.w R15 ; We assume that __romdatacopysize is never > 64M
-#endif
+#if Lmove_highdata
+;; Note - this section is only included in the startup code of the application
+;; if it is needed. It is responsible either for making sure that the
+;; contents of the .upper.data section have their correct startup values.
+;; If a copy of the .upper.data section is stored in ROM then this means
+;; copying the contents into HIFRAM. If a copy of .upper.data is stored in a
+;; shadow section in HIFRAM then this means copying from the shadow section
+;; into the real section.
+
+START_CRT_FUNC 0400 move_highdata
+ ;; __rom_highdatacopysize may be zero. Test this first because
+ ;; its value may come from the weak definitions above and we do
+ ;; not want to access the memory at address 0 pointed to by the
+ ;; weak definition of __upper_data_init.
+ mov.w #__rom_highdatacopysize, R14
+ cmp.w #0, R14
+ jeq 3f
+
+ /* Test our status word. */
+ cmpx.w #0, &__upper_data_init
+ jeq 1f
+ /* Status word is non-zero - copy from shadow into upper. */
+ mov_ #__high_datastart, R12
+ mov_ #__rom_highdatastart, R13
+ jmp 2f
+
+1: /* Status word is zero. Copy from upper to shadow and change status word. */
+ movx.w #1, &__upper_data_init
+ mov_ #__rom_highdatastart, R12
+ mov_ #__high_datastart, R13
+
+2: ;; __rom_highdatacopysize may be zero. memmove should cope.
+ mov.w #__rom_highdatacopysize, R14
+
call_ #memmove
-1:
-#endif
+3:
+END_CRT_FUNC move_highdata
+#endif /* Lmove_highdata */
+#endif /* __MSP430X_LARGE__ */
+
#if Lmain_minrt
- .section ".crt_0300main", "ax", @progbits
- .global __crt0_call_just_main
-__crt0_call_just_main:
+;; Note - this section is only included in the startup code of the
+;; application if it is needed. It is responsible for just calling
+;; main. No initialization code is called first, and main is not
+;; expected to return.
+
+START_CRT_FUNC 0600 call_just_main
+
clr.w R12 ; Set argc == 0
call_ #main
-#endif
+END_CRT_FUNC call_just_main
+#endif /* Lmain_minrt */
+
#if Lmain
- .section ".crt_0300main", "ax", @progbits
- .global __crt0_call_init_then_main
-__crt0_call_init_then_main:
+;; Note - this section is only included in the startup code of the
+;; application if it is needed. It is responsible for calling the
+;; initialization code - constructors, etc - and then main. If main
+;; returns then the following section should be present to catch it.
+
+START_CRT_FUNC 0700 call_init_then_main
+
call_ #__msp430_init
clr.w R12 ; Set argc == 0
call_ #main
-#endif
+
+END_CRT_FUNC call_init_then_main
+#endif /* Lmain */
+
#if Lcallexit
- .section ".crt_0400main_exit", "ax", @progbits
- .global __crt0_call_exit
-__crt0_call_exit:
+;; Note - this section is only included in the startup code of the
+;; application if it is needed. It is responsible for calling exit
+;; once main has finished.
+
+START_CRT_FUNC 0800 call_exit
+
call_ #_exit
-#endif
+
+END_CRT_FUNC call_exit
+#endif /* Lcallexit */
;----------------------------------------
#ifndef MINRT
#if L0
- .section ".crt_0500main_init", "ax", @progbits
+ .section ".crt_0900main_init", "ax", @progbits
.global _msp430_run_init_array
.type _msp430_run_init_array,@function
_msp430_run_init_array:
@@ -172,4 +268,4 @@ __msp430_fini:
call_ #_msp430_run_fini_array
#endif
-#endif
+#endif /* not MINRT */
diff --git a/libgloss/msp430/memmodel.h b/libgloss/msp430/memmodel.h
index 4804e17..a481460 100644
--- a/libgloss/msp430/memmodel.h
+++ b/libgloss/msp430/memmodel.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2012-2013 Red Hat, Inc. All rights reserved.
+/* Copyright (c) 2012-2015 Red Hat, Inc. All rights reserved.
This copyrighted material is made available to anyone wishing to use, modify,
copy, or redistribute it subject to the terms and conditions of the BSD
@@ -37,5 +37,30 @@
#define add_ ADD
#define PTRsz 2
-
#endif
+
+/* Start a function in its own named and numbered section, so that it
+ can be subject to linker garbage collection. The numbers are used
+ to enforce link-time ordering of the sections. Note - the construction
+ of the symbol names is critical - they need to match the unresolved
+ symbol references created by the compiler and assembler. */
+.macro START_CRT_FUNC number name
+ .section .crt_\number\name,"ax",@progbits
+ .global __crt0_\name
+ .type __crt0_\name , @function
+__crt0_\name:
+.endm
+
+
+/* End a named function. Sets the size so that GDB does not get confused. */
+.macro END_CRT_FUNC name
+ .size __crt0_\name, . - __crt0_\name
+.endm
+
+
+/* Provide a weak definition of NAME, initialized to zero. */
+.macro WEAK_DEF name
+ .global \name
+ .weak \name
+ \name = 0
+.endm
diff --git a/libgloss/msp430/msp430-sim.ld b/libgloss/msp430/msp430-sim.ld
index 01b3f21..6147cbe 100644
--- a/libgloss/msp430/msp430-sim.ld
+++ b/libgloss/msp430/msp430-sim.ld
@@ -1,4 +1,4 @@
-/* Copyright (c) 2013-2014 Red Hat, Inc. All rights reserved.
+/* Copyright (c) 2013-2015 Red Hat, Inc. All rights reserved.
This copyrighted material is made available to anyone wishing to use, modify,
copy, or redistribute it subject to the terms and conditions of the BSD
@@ -33,11 +33,15 @@ SECTIONS
{
. = ALIGN(2);
*(.plt)
+ . = ALIGN(2);
*(.lower.rodata.* .lower.rodata)
+ . = ALIGN(2);
*(.rodata .rodata.* .gnu.linkonce.r.* .const .const:*)
+ . = ALIGN(2);
+ *(.either.rodata.* .either.rodata)
+ . = ALIGN(2);
*(.rodata1)
- *(.eh_frame_hdr)
- KEEP (*(.eh_frame))
+
KEEP (*(.gcc_except_table)) *(.gcc_except_table.*)
PROVIDE (__preinit_array_start = .);
KEEP (*(.preinit_array))
@@ -52,6 +56,17 @@ SECTIONS
PROVIDE (__fini_array_end = .);
LONG(0); /* Sentinel. */
+ } > RAM
+
+ /* Note: This is a separate .rodata section for sections which are
+ read only but which older linkers treat as read-write.
+ This prevents older linkers from marking the entire .rodata
+ section as read-write. */
+ .rodata2 : {
+ . = ALIGN(2);
+ *(.eh_frame_hdr)
+ KEEP (*(.eh_frame))
+
/* gcc uses crtbegin.o to find the start of the constructors, so
we make sure it is first. Because this is a wildcard, it
doesn't matter if the user does not actually link against
@@ -80,8 +95,9 @@ SECTIONS
PROVIDE (_start = .);
KEEP (*(SORT(.crt_*)))
*(.lowtext)
- *(.lower.text.* .lower.text)
+ *(.lower.text.* .lower.text)
*(.text .stub .text.* .gnu.linkonce.t.* .text:*)
+ *(.either.text.* .either.text)
KEEP (*(.text.*personality*))
/* .gnu.warning sections are handled specially by elf32.em. */
*(.gnu.warning)
@@ -101,11 +117,15 @@ SECTIONS
PROVIDE (__datastart = .);
*(.lower.data.* .lower.data)
+
+ *(.data .data.* .gnu.linkonce.d.*)
+
+ *(.either.data.* .either.data)
+
KEEP (*(.jcr))
*(.data.rel.ro.local) *(.data.rel.ro*)
*(.dynamic)
- *(.data .data.* .gnu.linkonce.d.*)
KEEP (*(.gnu.linkonce.d.*personality*))
SORT(CONSTRUCTORS)
*(.data1)
@@ -136,6 +156,7 @@ SECTIONS
*(.dynbss)
*(.sbss .sbss.*)
*(.bss .bss.* .gnu.linkonce.b.*)
+ *(.either.bss.* .either.bss)
PROVIDE (__bssend = .);
} > RAM
PROVIDE (__bsssize = SIZEOF(.bss));
@@ -167,7 +188,7 @@ SECTIONS
*(.upper.data.* .upper.data)
*(.upper.bss.* .upper.bss)
*(.upper.text.* .upper.text)
- ASSERT (SIZEOF(.upper) == 0, ".upper sections present in a binary linked without -mlarge support");
+ ASSERT (SIZEOF(.upper) == 0, "This MCU does not support high memory");
}
/* The rest are all not normally part of the runtime image. */
diff --git a/libgloss/msp430/msp430xl-sim.ld b/libgloss/msp430/msp430xl-sim.ld
index 31ff85a..1dca58a 100644
--- a/libgloss/msp430/msp430xl-sim.ld
+++ b/libgloss/msp430/msp430xl-sim.ld
@@ -1,27 +1,35 @@
-/* Copyright (c) 2013-2014 Red Hat, Inc. All rights reserved.
+/* Copyright (c) 2013-2015 Red Hat, Inc. All rights reserved.
- This copyrighted material is made available to anyone wishing to use, modify,
- copy, or redistribute it subject to the terms and conditions of the BSD
- License. This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY expressed or implied, including the implied warranties
- of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. A copy of this license
- is available at http://www.opensource.org/licenses. Any Red Hat trademarks that
- are incorporated in the source code or documentation are not subject to the BSD
- License and may only be used or replicated with the express permission of
- Red Hat, Inc. */
+ This copyrighted material is made available to anyone wishing to use,
+ modify, copy, or redistribute it subject to the terms and conditions of
+ the BSD License. This program is distributed in the hope that it will be
+ useful, but WITHOUT ANY WARRANTY expressed or implied, including the
+ implied warranties of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ A copy of this license is available at http://www.opensource.org/licenses.
-/* Default linker script, for large MSP430X executables. */
+ Any Red Hat trademarks that are incorporated in the source code or
+ documentation are not subject to the BSD License and may only be used or
+ replicated with the express permission of Red Hat, Inc. */
+
+/* Example linker script, for large MSP430X executables. */
OUTPUT_ARCH(msp430)
ENTRY(_start)
INCLUDE intr_vectors.ld
+/* Note - These memory regions are just examples. Real MSP430 MCUs will have
+ different varieties and sizes of RAM, ROM and FLASH. Not all devices will
+ have all of these regions either. Device specific linker scripts are
+ provided by TI, so this file is intended to be used as a guide and so that
+ toolchain tests can be run against the simulator. */
MEMORY
{
- RAM (w) : ORIGIN = 0x00200, LENGTH = 0x01e00
+ RAM (rw) : ORIGIN = 0x00200, LENGTH = 0x01e00
ROM (rx) : ORIGIN = 0x02000, LENGTH = 0x0df00
- HIFRAM (rxw) : ORIGIN = 0x10000, LENGTH = 0x80000
+ /* The regions from intr_vectors.ld go here. */
+ HIFRAM (rw) : ORIGIN = 0x10000, LENGTH = 0x80000
+ HIROM (rx) : ORIGIN = 0x90000, LENGTH = 0x70000
}
SECTIONS
@@ -31,22 +39,34 @@ SECTIONS
*(.resetvec)
} > VECT31
- .upper.rodata :
- {
- . = ALIGN(2);
- *(.upper.rodata.* .upper.rodata)
- } > HIFRAM
-
.rodata :
{
. = ALIGN(2);
*(.plt)
+
+ . = ALIGN(2);
*(.lower.rodata.* .lower.rodata)
+
+ /* Note: By default we do not have this line:
+
+ *(.either.rodata.*) *(.either.rodata)
+
+ defined here, or anywhere else in this script. This is deliberate.
+ The algorithm in the linker that automatically places rodata into
+ either the .rodata or the .upper.rodata sections relies upon the
+ fact that the .either.rodata section is not defined, and that the
+ .upper.rodata section is defined. If the .upper.rodata is not
+ defined in this script then the line above should be restored so that
+ code compiled with -mdata-region=either enabled will still work.
+
+ The same reasoning applies to the absence of definitions for the
+ .either.text, .either.data and .either.bss sections as well. */
+
+ . = ALIGN(2);
*(.rodata .rodata.* .gnu.linkonce.r.* .const .const:*)
*(.rodata1)
- *(.eh_frame_hdr)
- KEEP (*(.eh_frame))
+ . = ALIGN(2);
KEEP (*(.gcc_except_table)) *(.gcc_except_table.*)
PROVIDE (__preinit_array_start = .);
KEEP (*(.preinit_array))
@@ -61,6 +81,17 @@ SECTIONS
PROVIDE (__fini_array_end = .);
LONG(0); /* Sentinel. */
+ } > ROM
+
+ /* Note: This is a separate .rodata section for sections which are
+ read only but which older linkers treat as read-write.
+ This prevents older linkers from marking the entire .rodata
+ section as read-write. */
+ .rodata2 : {
+ . = ALIGN(2);
+ *(.eh_frame_hdr)
+ KEEP (*(.eh_frame))
+
/* gcc uses crtbegin.o to find the start of the constructors, so
we make sure it is first. Because this is a wildcard, it
doesn't matter if the user does not actually link against
@@ -83,11 +114,19 @@ SECTIONS
KEEP (*(.dtors))
} > ROM
- .upper.data :
+ .upper.rodata :
{
+ /* Note: If this section is not defined then please add:
+
+ *(.either.rodata.*) *(.either.rodata)
+
+ to the definition of the .rodata section above. This
+ will allow code compiled with -mdata-region=either to
+ work properly. */
+
. = ALIGN(2);
- *(.upper.data.* .upper.data)
- } > HIFRAM
+ *(.upper.rodata.* .upper.rodata)
+ } > HIROM
.data :
{
@@ -100,7 +139,14 @@ SECTIONS
*(.data.rel.ro.local) *(.data.rel.ro*)
*(.dynamic)
+ . = ALIGN(2);
*(.data .data.* .gnu.linkonce.d.*)
+
+ /* See the note in .rodata section about why we do not have this line here:
+
+ *(.either.data.* .either.data)
+ */
+
KEEP (*(.gnu.linkonce.d.*personality*))
SORT(CONSTRUCTORS)
*(.data1)
@@ -113,24 +159,109 @@ SECTIONS
*(.sdata .sdata.* .gnu.linkonce.s.* D_2 D_1)
. = ALIGN(2);
-
_edata = .;
PROVIDE (edata = .);
PROVIDE (__dataend = .);
- } > RAM
-
- /* Note that crt0 assumes this is a multiple of two; all the
- start/stop symbols are also assumed word-aligned. */
- PROVIDE(__romdatastart = LOADADDR(.data));
- PROVIDE (__romdatacopysize = SIZEOF(.data));
- .upper.bss :
+ /* See the comment in the .upper.data section about the need
+ to copy data from ROM into RAM at program start up. */
+ } > RAM AT> ROM
+
+ /* Note that crt0 assumes that __romdatacopysize is a multiple of two.
+ All the start/stop symbols are also assumed to be word-aligned. */
+ __romdatastart = LOADADDR(.data);
+ __romdatacopysize = SIZEOF(.data);
+
+ /* ------------------- start of .upper.data sections.---------------- */
+ /* Note: If both HIROM and HIFRAM are available then the .upper.data
+ section should look like this:
+
+ . = ALIGN(2);
+ .upper.data :
+ {
+ __upper_data_init = LOADADDR (.upper.data);
+ /* Status word. * /
+ SHORT(1);
+ __high_datastart = .;
+ *(.upper.data.* .upper.data)
+ __high_dataend = .;
+ } > HIFRAM AT> HIROM
+
+ __rom_highdatacopysize = SIZEOF(.upper.data) - 2;
+ __rom_highdatastart = LOADADDR(.upper.data) + 2;
+
+ If only HIFRAM is available then the layout below must look like this:
+
+ .upper.data :
+ {
+ . = ALIGN(2);
+ __high_datastart = .;
+ *(.upper.data.* .upper.data)
+ __high_dataend = .;
+ } > HIFRAM
+
+ __rom_highdatacopysize = SIZEOF(.upper.data);
+
+ .shadow.upper.data :
+ {
+ . = ALIGN(2);
+ __upper_data_init = .;
+ /* Status word. * /
+ SHORT(0);
+ /* Space for the copy of .upper.data. * /
+ . = . + SIZEOF(.upper.data) - 2;
+ } > HIFRAM
+
+ __rom_highdatastart = LOADADDR(.shadow.upper.data) + 2;
+
+ Note - remove the space in this sequence: * / (twice) when you copy one
+ of the script fragments above into your script.
+
+ Note - the symbols defined here are *not* enclosed by the PROVIDE
+ keyword. This is deliberate. The crt0 library provides weak
+ definitions of these symbols and those weak definitions *must* be
+ overriden by the correct values.
+
+ The status word is used to control how the .upper.data section
+ is initialized at application start up. If the word is non-zero
+ then data is copied from __rom_highdatastart to __high_datastart.
+ This corresponds with copying the contents of .upper.data from its
+ load address (HIROM) to its run-time address (HIFRAM) in the first
+ scenario, or from the .shadow.upper.section to the .upper.data in
+ the second scenario.
+
+ If the status word is zero then the data is copied the other way
+ and the word is set to one. This only happens when the second
+ scenario is in play, and only the very first time the application
+ starts running. This makes sure that the .shadow.upper.data section
+ contains a pristine copy of the .upper.data section that can be used
+ to reinitialize the .upper.data section upon device reset.
+
+ The status word is necessary as this allows us to have one routine
+ in crt0 that can handle either form of .upper.data layout. IE crt0
+ is linker script agnostic.
+
+ Note - if the .upper.data section is not going to be defined at all
+ then please add this line back into the .data section above:
+
+ *(.either.data.* .either.data)
+ */
+
+ . = ALIGN(2);
+ .upper.data :
{
- . = ALIGN(2);
- PROVIDE (__high_bssstart = .);
- *(.upper.bss.* .upper.bss)
- PROVIDE (__high_bssend = .);
- } > HIFRAM
+ __upper_data_init = LOADADDR (.upper.data);
+ /* Status word. */
+ SHORT(1);
+ __high_datastart = .;
+ *(.upper.data.* .upper.data)
+ __high_dataend = .;
+ } > HIFRAM AT> HIROM
+
+ __rom_highdatacopysize = SIZEOF(.upper.data) - 2;
+ __rom_highdatastart = LOADADDR(.upper.data) + 2;
+
+ /* ------------------- end of .upper.data sections.---------------- */
.bss :
{
@@ -140,53 +271,87 @@ SECTIONS
*(.dynbss)
*(.sbss .sbss.*)
*(.bss .bss.* .gnu.linkonce.b.*)
+ /* See the note in .rodata section about why we do not have this line here:
+
+ *(.either.bss.* .either.bss)
+ */
+ . = ALIGN(2);
+ *(COMMON)
. = ALIGN(2);
PROVIDE (__bssend = .);
} > RAM
PROVIDE (__bsssize = SIZEOF(.bss));
- /* This section contains data that is not initialised at startup. */
+ /* This section contains data that is not initialised at startup
+ *or* application reset. */
.noinit (NOLOAD) :
{
. = ALIGN(2);
PROVIDE (__noinit_start = .);
*(.noinit)
. = ALIGN(2);
- *(COMMON)
PROVIDE (__noinit_end = .);
} > RAM
- _end = .;
- PROVIDE (end = .);
+ .upper.bss :
+ {
+ /* Note - if this section is not going to be defined then please
+ add this line back into the definition of the .bss section above:
+
+ *(.either.bss.* .either.bss)
+ */
+ . = ALIGN(2);
+ __high_bssstart = .;
+ *(.upper.bss.* .upper.bss)
+ . = ALIGN(2);
+ __high_bssend = .;
+ } > HIFRAM
+
+ /* We create this section so that "end" will always be in the
+ HIFRAM region (matching .stack below), even if the .upper.bss
+ section is empty. */
+ .heap_start :
+ {
+ . = ALIGN(2);
+ _end = .;
+ PROVIDE (end = .);
+ LONG(0);
+ } > HIFRAM
+
+ /* Note: We place the stack in HIFRAM because then there is less
+ chance that it will collide with allocated data in the RAM region.
+ In scripts targeted at real MCUs however it may be better to place
+ the stack and heap in RAM, as flash does have a limited number of
+ writes before failure.
- .stack (ORIGIN (HIFRAM) + LENGTH(HIFRAM)) :
+ Note - if the location of .stack is changed, then be sure to change
+ the definition of .heap_start above as well. */
+ .stack (ORIGIN (HIFRAM) + LENGTH (HIFRAM)) :
{
PROVIDE (__stack = .);
- *(.stack)
}
- /* This is just for crt0.S and interrupt handlers. */
- .lowtext :
+ .text :
{
PROVIDE (_start = .);
+
. = ALIGN(2);
KEEP (*(SORT(.crt_*)))
- KEEP (*(.lowtext))
- } > ROM
- .upper.text :
- {
. = ALIGN(2);
- *(.upper.text.* .upper.text)
- } > HIFRAM
+ KEEP (*(.lowtext))
- .text :
- {
. = ALIGN(2);
*(.lower.text.* .lower.text)
+
. = ALIGN(2);
*(.text .stub .text.* .gnu.linkonce.t.* .text:*)
+ /* See the note in .rodata section about why we do not have this line here:
+
+ *(.either.text.* .either.text)
+ */
+
KEEP (*(.text.*personality*))
/* .gnu.warning sections are handled specially by elf32.em. */
*(.gnu.warning)
@@ -200,6 +365,18 @@ SECTIONS
KEEP (*(.tm_clone_table))
} > ROM
+ .upper.text :
+ {
+ /* Note - if this section is not going to be included in the script
+ then please add this line back into the definition of the .text
+ section above:
+
+ *(.either.text.* .either.text)
+ */
+ . = ALIGN(2);
+ *(.upper.text.* .upper.text)
+ } > HIROM
+
/* The rest are all not normally part of the runtime image. */
.MP430.attributes 0 :