objcopy vs absolute addresses

[Игорь Пашев <pashev.igor@gmail.com>]

Hi, all.

While trying to build GRUB on illumos [*-pc-solaris2.11], I've found that
for different absolute addresses (-Wl,-Ttext -Wl,<ADDR>) objcopy -O binary
produces different objects files, but it is expected to be the same.

Test script see at the bottom.

I've checked it with binutils 2.22 on Debian and on Gentoo with
different compilers.

Debian's binutils have this problem, Gentoo:

Gentoo:
# ./objcopy-test
+ CC='gcc -m32'
+ OBJCOPY=objcopy
+ cat
+ gcc -m32 -c conftest.c -o conftest.o
+ for link_addr in 2000 8000 7C00
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,2000 conftest.o -o conftest.exec.2000
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../x86_64-pc-linux-gnu/bin/ld:
warning: cannot find entry symbol _start; defaulting to
0000000000002000
+ objcopy -O binary conftest.exec.2000 conftest.2000
+ for link_addr in 2000 8000 7C00
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,8000 conftest.o -o conftest.exec.8000
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../x86_64-pc-linux-gnu/bin/ld:
warning: cannot find entry symbol _start; defaulting to
0000000000008000
+ objcopy -O binary conftest.exec.8000 conftest.8000
+ for link_addr in 2000 8000 7C00
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,7C00 conftest.o -o conftest.exec.7C00
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../x86_64-pc-linux-gnu/bin/ld:
warning: cannot find entry symbol _start; defaulting to
0000000000007c00
+ objcopy -O binary conftest.exec.7C00 conftest.7C00
+ md5sum conftest.2000 conftest.7C00 conftest.8000
05349871a5ab8bb0c860d3109d65f58d  conftest.2000
05349871a5ab8bb0c860d3109d65f58d  conftest.7C00
05349871a5ab8bb0c860d3109d65f58d  conftest.8000
+ exit 0


Debian (testing):
# ./objcopy-test
+ CC=gcc -m32
+ OBJCOPY=objcopy
+ cat
+ gcc -m32 -c conftest.c -o conftest.o
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,2000 conftest.o -o conftest.exec.2000
/usr/bin/ld.bfd.real: warning: cannot find entry symbol _start;
defaulting to 0000000000002000
+ objcopy -O binary conftest.exec.2000 conftest.2000
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,8000 conftest.o -o conftest.exec.8000
/usr/bin/ld.bfd.real: warning: cannot find entry symbol _start;
defaulting to 0000000000008000
+ objcopy -O binary conftest.exec.8000 conftest.8000
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,7C00 conftest.o -o conftest.exec.7C00
/usr/bin/ld.bfd.real: warning: cannot find entry symbol _start;
defaulting to 0000000000007c00
+ objcopy -O binary conftest.exec.7C00 conftest.7C00
+ md5sum conftest.2000 conftest.7C00 conftest.8000
c2d829df4c6a7e335ab0e6a944ec87a3  conftest.2000
a6a514773337be95da81db75cdd011ba  conftest.7C00
5883efd0da029145374269a65f8d689b  conftest.8000
+ exit 0


I've event tested it on OpenIndiana (binutils 2.19, GCC 4.4):
# LD_ALTEXEC=/usr/bin/gld ./objcopy-test
+ CC='gcc -m32'
+ OBJCOPY=objcopy
+ cat
+ 1> conftest.c 0<< \EOF
void
cmain (void)
{
   *((int *) 0x1000) = 2;
}
EOF
+ gcc -m32 -c conftest.c -o conftest.o
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,2000 conftest.o -o conftest.exec.2000
/usr/bin/gld: warning: cannot find entry symbol _start; defaulting to
0000000000002000
+ objcopy -O binary conftest.exec.2000 conftest.2000
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,8000 conftest.o -o conftest.exec.8000
/usr/bin/gld: warning: cannot find entry symbol _start; defaulting to
0000000000008000
+ objcopy -O binary conftest.exec.8000 conftest.8000
+ gcc -m32 -nostdlib -Wl,-N -Wl,-Ttext -Wl,7C00 conftest.o -o conftest.exec.7C00
/usr/bin/gld: warning: cannot find entry symbol _start; defaulting to
0000000000007c00
+ objcopy -O binary conftest.exec.7C00 conftest.7C00
+ md5sum conftest.2000 conftest.7C00 conftest.8000
42a9a3664e7dc9327f62aa111493b7b0  conftest.2000
42a9a3664e7dc9327f62aa111493b7b0  conftest.7C00
42a9a3664e7dc9327f62aa111493b7b0  conftest.8000
+ exit 0




Could you check this out (run the script)?
I'm thinking it could be cause by one of Debian patches.


Here the test script (from GRUB's configure):
======================== >8 ==========================
#!/bin/sh

set -u
set -e
set -x

CC=${CC-gcc -m32}
OBJCOPY=${OBJCOPY-objcopy}

cat > conftest.c <<\EOF
void
cmain (void)
{
   *((int *) 0x1000) = 2;
}
EOF

$CC -c conftest.c -o conftest.o

for link_addr in 2000 8000 7C00; do
    $CC -nostdlib -Wl,-N -Wl,-Ttext -Wl,$link_addr conftest.o -o
conftest.exec.$link_addr
    $OBJCOPY -O binary conftest.exec.$link_addr conftest.$link_addr
done

md5sum conftest.[0-9]*

exit 0
======================== 8< ==========================