Re: dynamic linking

[Tomas By]

Hello again,

I have now tried to link my Mercury library with the libgc that Guile
uses instead of the Mercury one, and I asked about it on the Mercury
mailing list, where I got this reply:

"The version of libgc that Mercury uses contains Mercury specific
modifications; I would be surprised if linking against the system
wide one worked."

The final parts of both strace outputs are included below.

The version of Guile I am using is 1.8.7 -- is it worth trying 1.9
instead?

Is it generally possible to use two different libgc at the same time?

Grateful for any help with this.

/Tomas

---------- begin Mercury GC ---------------------------------------
open("/usr/local/mercury-rotd-2009-12-28/lib/mercury/lib/libgc.so",
O_RDONLY) = 9
read(9,
"address@hidden"..., 512)
= 512
fstat64(9, {st_mode=S_IFREG|0755, st_size=121223, ...}) = 0
mmap2(NULL, 464944, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 9, 0)
= 0x9a4000
mmap2(0x9bb000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 9, 0x17) = 0x9bb000
mmap2(0x9bd000, 362544, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x9bd000
close(9)                                = 0
mprotect(0x9bb000, 4096, PROT_READ)     = 0
mprotect(0x298000, 4096, PROT_READ)     = 0
mprotect(0x11b2000, 126976, PROT_READ)  = 0
mprotect(0x422000, 20480, PROT_READ|PROT_WRITE) = 0
munmap(0x422000, 24684)                 = 0
munmap(0xdec000, 6385312)               = 0
munmap(0x255000, 287840)                = 0
munmap(0x9a4000, 464944)                = 0
----------------------------------------------------------------

---------- begin Guile GC -----------------------------------------
open("/usr/lib/libgc.so", O_RDONLY)     = 9
read(9, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0
\200\0\0004\0\0\0"..., 512) = 512
fstat64(9, {st_mode=S_IFREG|0644, st_size=137280, ...}) = 0
mmap2(NULL, 206620, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 9, 0)
= 0x49b000
mmap2(0x4bc000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 9, 0x20) = 0x4bc000
mmap2(0x4be000, 63260, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x4be000
close(9)                                = 0
open("/usr/local/mercury-rotd-2009-12-28/lib/mercury/lib/libgcc_s.so.1",
O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/local/mercury-rotd-2009-12-28/lib/mercury/lib/asm_fast.gc/libgcc_s.so.1",
O_RDONLY) = -1 ENOENT (No such file or directory)
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or
directory)
open("/lib/libgcc_s.so.1", O_RDONLY)    = 9
read(9,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0p#\0\0004\0\0\0"..., 512)
= 512
fstat64(9, {st_mode=S_IFREG|0644, st_size=116272, ...}) = 0
mmap2(NULL, 119336, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 9, 0)
= 0xe5b000
mmap2(0xe77000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 9, 0x1b) = 0xe77000
close(9)                                = 0
mprotect(0xe77000, 4096, PROT_READ)     = 0
mprotect(0x4bc000, 4096, PROT_READ)     = 0
munmap(0xb782b000, 91754)               = 0
munmap(0xab8000, 24684)                 = 0
munmap(0xf83000, 6385312)               = 0
munmap(0x304000, 287840)                = 0
munmap(0x49b000, 206620)                = 0
munmap(0xe5b000, 119336)                = 0
------------------------------------------------------------------

On Fri, February 5, 2010 14:57, Ludovic Courtès wrote:
> Hi,
>
> "Tomas By" <address@hidden> writes:
>
>> open("/usr/local/mercury-rotd-2009-12-28/lib/mercury/lib/libgc.so",
>> O_RDONLY) = 9
>
> [...]
>
>> I guess that "libgc.so" is the Mercury garbage collector. Is there some
>> problem with having another GC in a Guile module?
>
> The problem is that Guile 1.9 is linked against another libgc (this one:
> http://www.hpl.hp.com/personal/Hans_Boehm/gc/).  So, presumably, when
> dlopening the Guile module, the dynamic linker tries top open libgc.so
> but picks up the wrong one, hence the failure.
>
> Thanks,
> Ludo’.
>
>
>
>