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Re: Regression on prelinked-sepdebug-shlibs
On Jan 7, 2010, at 2:42 PM, Daniel Jacobowitz wrote:
> On Thu, Jan 07, 2010 at 12:03:04PM +0100, Tristan Gingold wrote:
>> I am not sure that you can create a linux native executable with a section whose vma is 0.
>
> I'm pretty sure you can't. The program headers are going to be at the
> start of the executable, before any section. So I'm not entirely sure
> what kind of executable you get from doing this :-)
You lost me. They can be on different pages ?
In fact I can build such a statically linked program. However it looks like ld.so or libc doesn't like
such a program (also it is buildable).
$ cat sep.c
int zero (void) __attribute__((section("sec_zero")));
int zero (void)
{
return 12;
}
void _start (void)
{
asm volatile ("int $0x80" : : "a"(1), "b"(zero()));
}
$ gcc -c -g -m32 sep.c
$ gcc -m32 -o sep sep.o -Wl,--section-start,sec_zero=0 -nostdlib
$ readelf -S sep
There are 14 section headers, starting at offset 0x136c:
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000 00 0 0 0
[ 1] sec_zero PROGBITS 00000000 001000 00000a 00 AX 0 0 1
[ 2] .text PROGBITS 08048094 001094 000015 00 AX 0 0 4
[ 3] .comment PROGBITS 00000000 0010a9 00002e 00 0 0 1
[ 4] .debug_aranges PROGBITS 00000000 0010d7 000028 00 0 0 1
[ 5] .debug_pubnames PROGBITS 00000000 0010ff 000026 00 0 0 1
[ 6] .debug_info PROGBITS 00000000 001125 00008c 00 0 0 1
[ 7] .debug_abbrev PROGBITS 00000000 0011b1 000047 00 0 0 1
[ 8] .debug_line PROGBITS 00000000 0011f8 000044 00 0 0 1
[ 9] .debug_frame PROGBITS 00000000 00123c 000048 00 0 0 4
[10] .debug_loc PROGBITS 00000000 001284 000058 00 0 0 1
[11] .shstrtab STRTAB 00000000 0012dc 000090 00 0 0 1
[12] .symtab SYMTAB 00000000 00159c 000110 10 13 12 4
[13] .strtab STRTAB 00000000 0016ac 00002b 00 0 0 1
Tristan.