Des connaissances améliorées L'utilisation conjointe de ld et ldd de Linux peut nous aider à analyser les raisons de l'échec du chargement des fichiers de bibliothèque au moment de l'exécution.

Habituellement, lorsque les développeurs et le personnel d'exploitation et de maintenance sont confrontés au problème de l'impossibilité de trouver les bibliothèques dépendantes lors de l'exécution d'un logiciel, ils peuvent utiliser certains outils pour suivre le processus de chargement au démarrage, tels que strace, gdb, etc. De plus, vous pouvez également utiliser les commandes ld et ldd pour vous aider à analyser la situation des bibliothèques dépendantes afin de résoudre le problème plus rapidement. Ces outils peuvent aider à localiser les bibliothèques de dépendances manquantes et guider les utilisateurs dans la prise des mesures appropriées pour résoudre les problèmes d'exécution des logiciels.

Ici, nous analyserons le fichier de bibliothèque dynamique libmpi_usempif80.so et les autres bibliothèques dynamiques dont il dépend comme cause du problème.

Présentez d'abord comment la commande ld peut nous aider à analyser de quelles autres bibliothèques dépend la bibliothèque mpi_usempif80 ? Lorsque la bibliothèque mpi_usempif80 est chargée, quels chemins dans le système actuel ces bibliothèques seront-elles recherchées ?

#ld -lmpi_usempif08 –verbeux

GNU ld (GNU Binutils for Ubuntu) 2.38
Supported emulations:
 elf_x86_64
 elf32_x86_64
 elf_i386
 elf_iamcu
 elf_l1om
 elf_k1om
 i386pep
 i386pe
using internal linker script:
==================================================
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 Copying and distribution of this script, with or without modification,
 are permitted in any medium without royalty provided the copyright
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OUTPUT_ARCH(i386:x86-64)
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PROVIDE_HIDDEN (__init_array_end = .);
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KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
PROVIDE_HIDDEN (__fini_array_end = .);
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KEEP (*crtbegin?.o(.ctors))
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KEEP (*(SORT(.ctors.*)))
KEEP (*(.ctors))
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KEEP (*crtbegin.o(.dtors))
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KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
KEEP (*(SORT(.dtors.*)))
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FIXME: Why do we need it? When there is no .bss section, we do not
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}


==================================================
ld: mode elf_x86_64
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.so failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.a failed
attempt to open /lib/x86_64-linux-gnu/libmpi_usempif08.so succeeded
/lib/x86_64-linux-gnu/libmpi_usempif08.so
libmpi_mpifh.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi_mpifh.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi_mpifh.so.40 failed
attempt to open /usr/local/lib/libmpi_mpifh.so.40 failed
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
libmpi.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi.so.40 failed
attempt to open /usr/local/lib/libmpi.so.40 failed
found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40
libc.so.6 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libc.so.6 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libc.so.6 failed
attempt to open /usr/local/lib/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/fortran/gfortran/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libc.so.6 failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu64/libc.so.6 failed
attempt to open /usr/local/lib64/libc.so.6 failed
attempt to open /lib64/libc.so.6 failed
attempt to open /usr/lib64/libc.so.6 failed
attempt to open /usr/local/lib/libc.so.6 failed
attempt to open /lib/libc.so.6 failed
attempt to open /usr/lib/libc.so.6 failed
attempt to open /usr/x86_64-linux-gnu/lib64/libc.so.6 failed
attempt to open /usr/x86_64-linux-gnu/lib/libc.so.6 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libc.so.6 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libc.so.6 failed
attempt to open /usr/local/lib/libc.so.6 failed
found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6
libopen-pal.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libopen-pal.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/opal/.libs/libopen-pal.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libopen-pal.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libopen-pal.so.40 failed
attempt to open /usr/local/lib/libopen-pal.so.40 failed
found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
libopen-rte.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libopen-rte.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libopen-rte.so.40 failed
attempt to open /usr/local/lib/libopen-rte.so.40 failed
found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
libm.so.6 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libm.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libm.so.6 failed
attempt to open /usr/local/lib/libm.so.6 failed
found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6
libhwloc.so.15 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libhwloc.so.15 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libhwloc.so.15 failed
attempt to open /usr/local/lib/libhwloc.so.15 failed
found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15
ld-linux-x86-64.so.2 needed by /usr/lib/x86_64-linux-gnu/libc.so.6
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/ld-linux-x86-64.so.2 failed
attempt to open /usr/local/lib/ld-linux-x86-64.so.2 failed
found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
libevent_core-2.1.so.7 needed by /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libevent_core-2.1.so.7 failed
attempt to open /usr/local/lib/libevent_core-2.1.so.7 failed
found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7
libevent_pthreads-2.1.so.7 needed by /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libevent_pthreads-2.1.so.7 failed
attempt to open /usr/local/lib/libevent_pthreads-2.1.so.7 failed
found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7
libz.so.1 needed by /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libz.so.1 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libz.so.1 failed
attempt to open /usr/local/lib/libz.so.1 failed
found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1
libudev.so.1 needed by /usr/lib/x86_64-linux-gnu/libhwloc.so.15
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libudev.so.1 failed
attempt to open /usr/local/lib/libudev.so.1 failed
found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1


ld -lmpi_usempif08 --verbose | grep found
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40
ld: warning: cannot find entry symbol _start; not setting start address
found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6
found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6
found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15
found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7
found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7
found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1
found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1

Les informations ci-dessus sont très longues et contiennent de nombreuses informations précieuses. Si vous souhaitez uniquement voir les parties clés, je conserverai le contenu clé et proposerai une version condensée des informations de sortie :

#ld -lmpi_usempif08 –verbeux

GNU ld (GNU Binutils for Ubuntu) 2.38
Supported emulations:
 elf_x86_64
……
using internal linker script:

 notice and this notice are preserved.*/
OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64",
 "elf64-x86-64")
OUTPUT_ARCH(i386:x86-64)
ENTRY(_start)# 运行时可执行文件从代码段的 _start 位置开始运行。

# 运行时需从哪些目录找动态库文件
SEARCH_DIR("=/usr/local/lib/x86_64-linux-gnu"); SEARCH_DIR("=/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu64"); SEARCH_DIR("=/usr/local/lib64"); SEARCH_DIR("=/lib64"); SEARCH_DIR("=/usr/lib64"); SEARCH_DIR("=/usr/local/lib"); SEARCH_DIR("=/lib"); SEARCH_DIR("=/usr/lib"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib64"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib");

# 二进制文件有哪些的代码段、数据段
SECTIONS
{
PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x400000)); . = SEGMENT_START("text-segment", 0x400000) + SIZEOF_HEADERS;
.interp : { *(.interp) }
……
.rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }

……
/* Thread Local Storage sections*/
# 线程本地存储区域
.tdata :
 {
 PROVIDE_HIDDEN (__tdata_start = .);
 *(.tdata .tdata.* .gnu.linkonce.td.*)
 }
.tbss: { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) }
.preinit_array:
{
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array))
PROVIDE_HIDDEN (__preinit_array_end = .);
}
# 数据区
.data :
{
*(.data .data.* .gnu.linkonce.d.*)
SORT(CONSTRUCTORS)
}
.data1: { *(.data1) }
_edata = .; PROVIDE (edata = .);
. = .;
__bss_start = .;

# BSS区
.bss:
{
 ……
}
 ……
}

# 下面是本文的重点关注部分
==================================================

# 文件1：逐个目录匹配是否找到被依赖的libmpi_usempif08.so 库文件
ld: mode elf_x86_64
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.so failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.a failed
attempt to open /lib/x86_64-linux-gnu/libmpi_usempif08.so succeeded
# 找到了 libmpi_usempif08.so 库文件

# 文件2：逐个目录匹配是否找到被依赖的 libmpi_mpifh.so 库文件
libmpi_mpifh.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi_mpifh.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi_mpifh.so.40 failed
attempt to open /usr/local/lib/libmpi_mpifh.so.40 failed
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
# 找到了 libmpi_mpifh.so 库文件

# 找 libmpi.so.40 
libmpi.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
……
found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40

# 找 libc.so.6 
libc.so.6 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
……
found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6

# 找 libopen-pal.so.40
libopen-pal.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
……
found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40

# 找 libopen-rte.so.40
libopen-rte.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
……
found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40

# 找 libm.so.6
libm.so.6 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
……
found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6
libhwloc.so.15 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40

# 找 libhwloc.so.15
……略

# 找 libudev.so.1
libudev.so.1 needed by /usr/lib/x86_64-linux-gnu/libhwloc.so.15
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libudev.so.1 failed
attempt to open /usr/local/lib/libudev.so.1 failed
found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1

De plus, nous pouvons utiliser grep pour filtrer afin d'afficher uniquement les informations sur les bibliothèques réellement trouvées par mpi_usempif08 :

#ld -lmpi_usempif08 –verbeux | grep trouvé

found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40
ld: warning: cannot find entry symbol _start; not setting start address
found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6
found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6
found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15
found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7
found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7
found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1
found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1

Et ldd est différent de ld. ldd analyse les dépendances des bibliothèques d'exécution Linux, et ld est un éditeur de liens de fichiers exécutables qui est souvent utilisé dans la phase de liaison pour générer des fichiers exécutables à partir de C/C++/Fortran et d'autres codes de langage.

Jetons un coup d'œil à l'utilisation de ldd pour analyser d'autres bibliothèques dont dépend la même bibliothèque dynamique :

#ldd/usr/lib/x86_64-linux-gnu/libmpi_usempif08.so.40.30.0

 linux-vdso.so.1 (0x00007ffd2f3fd000)
 libmpi_mpifh.so.40 => /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40 (0x00007f34366bf000)
 libmpi.so.40 => /usr/lib/x86_64-linux-gnu/libmpi.so.40 (0x00007f3436588000)
 libc.so.6 => /usr/lib/x86_64-linux-gnu/libc.so.6 (0x00007f3436200000)
 libopen-pal.so.40 => /usr/lib/x86_64-linux-gnu/libopen-pal.so.40 (0x00007f34364d5000)
 libopen-rte.so.40 => /usr/lib/x86_64-linux-gnu/libopen-rte.so.40 (0x00007f3436143000)
 libm.so.6 => /usr/lib/x86_64-linux-gnu/libm.so.6 (0x00007f343605c000)
 libhwloc.so.15 => /usr/lib/x86_64-linux-gnu/libhwloc.so.15 (0x00007f3436477000)
 /lib64/ld-linux-x86-64.so.2 (0x00007f343677c000)
 libevent_core-2.1.so.7 => /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7 (0x00007f3436442000)
 libevent_pthreads-2.1.so.7 => /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7 (0x00007f343643d000)
 libz.so.1 => /usr/lib/x86_64-linux-gnu/libz.so.1 (0x00007f3436040000)
 libudev.so.1 => /usr/lib/x86_64-linux-gnu/libudev.so.1 (0x00007f3436016000)

L'ordre ici est cohérent avec le résultat de ld -lmpi_usempif08 –verbose grep trouvé.

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