Hi there,
Not sure if this is generic to any gcc target, or it just happens for
avr, given previous mentioned problems with the .data section
dissappearing (due to -gc-sections) causing .bss to be resolved to the
wrong addresses for avr...
Anyway, this is my test case and what happens, which does not happen in
the Atmel latest published toolchain:
Test program is:
$ cat gcc-data-sections.c
#if MAKE_A_PROBLEM
#if MAKE_IT_WORK
__attribute__((section(".my.tables.things.data")))
#endif/*MAKE_IT_WORK*/
extern unsigned long my_thing_1;
static unsigned long *my_local_thing = &my_thing_1;
#else /*MAKE_A_PROBLEM*/
static unsigned long *my_local_thing;
#endif/*MAKE_A_PROBLEM*/
__attribute__((section(".my.tables.things.data")))
unsigned long my_thing_1 = 0x600df00d;
void my_dummy(void)
{
(void) my_local_thing; /*avoid a warning*/
}
When compiling with:
$ avr-gcc -mmcu=atxmega256a3u -Wa,-mmcu=atxmega256a3u -Os -g
-fsigned-char -ffunction-sections -fdata-sections -Wall -Wextra -Werror
-std=gnu99 -DMAKE_A_PROBLEM=1 -DMAKE_IT_WORK=0 -c -o gcc-data-sections.o
gcc-data-sections.c
as it is usually done (and does work in the atmel toolchain), I get:
$ avr-objdump -h gcc-data-sections.o
gcc-data-sections.o: file format elf32-avr
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000000 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .data 00000000 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, DATA
2 .bss 00000000 00000000 00000000 00000034 2**0
ALLOC
3 .text.my_dummy 00000002 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
4 .data.my_thing_1 00000004 00000000 00000000 00000036 2**0
CONTENTS, ALLOC, LOAD, DATA
5 .debug_info 00000067 00000000 00000000 0000003a 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
6 .debug_abbrev 00000060 00000000 00000000 000000a1 2**0
CONTENTS, READONLY, DEBUGGING
7 .debug_aranges 00000020 00000000 00000000 00000101 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
8 .debug_ranges 00000010 00000000 00000000 00000121 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
9 .debug_line 00000043 00000000 00000000 00000131 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
10 .debug_str 000000e7 00000000 00000000 00000174 2**0
CONTENTS, READONLY, DEBUGGING
11 .comment 0000002b 00000000 00000000 0000025b 2**0
CONTENTS, READONLY
12 .debug_frame 00000024 00000000 00000000 00000288 2**2
CONTENTS, RELOC, READONLY, DEBUGGING
With my_thing_1 not going into its assigned section as it should. Found
that is due to the previous extern declaration, which seems to work if
it is removed:
$ avr-gcc -mmcu=atxmega256a3u -Wa,-mmcu=atxmega256a3u -Os -g
-fsigned-char -ffunction-sections -fdata-sections -Wall -Wextra -Werror
-std=gnu99 -DMAKE_A_PROBLEM=0 -DMAKE_IT_WORK=0 -c -o gcc-data-sections.o
gcc-data-sections.c
$ avr-objdump -h gcc-data-sections.o
gcc-data-sections.o: file format elf32-avr
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000000 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .data 00000000 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, DATA
2 .bss 00000000 00000000 00000000 00000034 2**0
ALLOC
3 .text.my_dummy 00000002 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
4 .my.tables.things.data 00000004 00000000 00000000 00000036 2**0
CONTENTS, ALLOC, LOAD, DATA
5 .debug_info 00000060 00000000 00000000 0000003a 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
6 .debug_abbrev 0000005e 00000000 00000000 0000009a 2**0
CONTENTS, READONLY, DEBUGGING
7 .debug_aranges 00000020 00000000 00000000 000000f8 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
8 .debug_ranges 00000010 00000000 00000000 00000118 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
9 .debug_line 00000043 00000000 00000000 00000128 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
10 .debug_str 000000e7 00000000 00000000 0000016b 2**0
CONTENTS, READONLY, DEBUGGING
11 .comment 0000002b 00000000 00000000 00000252 2**0
CONTENTS, READONLY
12 .debug_frame 00000024 00000000 00000000 00000280 2**2
CONTENTS, RELOC, READONLY, DEBUGGING
or if it is annotated with the same section attribute:
$ avr-gcc -mmcu=atxmega256a3u -Wa,-mmcu=atxmega256a3u -Os -g
-fsigned-char -ffunction-sections -fdata-sections -Wall -Wextra -Werror
-std=gnu99 -DMAKE_A_PROBLEM=1 -DMAKE_IT_WORK=1 -c -o gcc-data-sections.o
gcc-data-sections.c
$ avr-objdump -h gcc-data-sections.o
gcc-data-sections.o: file format elf32-avr
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000000 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .data 00000000 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, DATA
2 .bss 00000000 00000000 00000000 00000034 2**0
ALLOC
3 .text.my_dummy 00000002 00000000 00000000 00000034 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
4 .my.tables.things.data 00000004 00000000 00000000 00000036 2**0
CONTENTS, ALLOC, LOAD, DATA
5 .debug_info 00000067 00000000 00000000 0000003a 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
6 .debug_abbrev 00000060 00000000 00000000 000000a1 2**0
CONTENTS, READONLY, DEBUGGING
7 .debug_aranges 00000020 00000000 00000000 00000101 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
8 .debug_ranges 00000010 00000000 00000000 00000121 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
9 .debug_line 00000043 00000000 00000000 00000131 2**0
CONTENTS, RELOC, READONLY, DEBUGGING
10 .debug_str 000000e7 00000000 00000000 00000174 2**0
CONTENTS, READONLY, DEBUGGING
11 .comment 0000002b 00000000 00000000 0000025b 2**0
CONTENTS, READONLY
12 .debug_frame 00000024 00000000 00000000 00000288 2**2
CONTENTS, RELOC, READONLY, DEBUGGING
The trunk version that I built (using also trunk binutils
and trunk avr-libc) is:
$ avr-gcc -v
Using built-in specs.
COLLECT_GCC=avr-gcc
COLLECT_LTO_WRAPPER=/misc/apps/avr8/tools_002/libexec/gcc/avr/4.10.0/lto-wrapper
Target: avr
Configured with: /home/df/src/gcc-trunk/configure
--prefix=/misc/apps/avr8/tools_002 --target=avr --enable-languages=c,c++
--with-gnu-as --with-gnu-ld --with-dwarf2 --with-avrlibc=yes
--enable-fixed-point --enable-doc --disable-libssp --disable-libada
--disable-shared -v
Thread model: single
gcc version 4.10.0 20140729 (experimental) (GCC)
The atmel gcc is:
$ avr-gcc -v
Using built-in specs.
COLLECT_GCC=avr-gcc
COLLECT_LTO_WRAPPER=/misc/apps/avr8/avr8-gnu-toolchain-linux_x86_64/bin/../libexec/gcc/avr/4.8.1/lto-wrapper
Target: avr
Configured with:
/data2/home/toolsbuild/jenkins-knuth/workspace/avr8-gnu-toolchain/src/gcc/configure
LDFLAGS=-L/home/toolsbuild/jenkins-knuth/workspace/avr8-gnu-toolchain/avr8-gnu-toolchain-linux_x86_64/lib
CPPFLAGS= --target=avr --host=x86_64-pc-linux-gnu
--build=x86_64-pc-linux-gnu
--prefix=/home/toolsbuild/jenkins-knuth/workspace/avr8-gnu-toolchain/avr8-gnu-toolchain-linux_x86_64
--libdir=/home/toolsbuild/jenkins-knuth/workspace/avr8-gnu-toolchain/avr8-gnu-toolchain-linux_x86_64/lib
--enable-languages=c,c++ --with-dwarf2 --enable-doc --disable-shared
--disable-libada --disable-libssp --disable-nls --with-avrlibc=yes
--with-mpfr=/home/toolsbuild/jenkins-knuth/workspace/avr8-gnu-toolchain/avr8-gnu-toolchain-linux_x86_64
--with-gmp=/home/toolsbuild/jenkins-knuth/workspace/avr8-gnu-toolchain/avr8-gnu-toolchain-linux_x86_64
--with-mpc=/home/toolsbuild/jenkins-knuth/workspace/avr8-gnu-toolchain/avr8-gnu-toolchain-linux_x86_64
--enable-fixed-point
--with-pkgversion=AVR_8_bit_GNU_Toolchain_3.4.3_1072
--with-bugurl=http://www.atmel.com
Thread model: single
gcc version 4.8.1 (AVR_8_bit_GNU_Toolchain_3.4.3_1072)
Other than that (and a bit pickier with aggregate initializers that
don't include all the elements), it builds functional firmware properly.
So I guess I would like you guys to confirm that this is a bug or regression,
and let me know the bug reference if any.
Greetings
David Fernandez
