SYSV与Linux / GNU ELF格式 [英] SYSV vs. Linux/GNU ELF formats

问题描述

该问题与以下问题相关：为什么找不到库，即使它们显然在-L路径上也是如此？。看来我的库和目标文件具有不同的ELF格式，这可能会导致链接器无法找到库。

The question is in the context of the following question: Why are libraries not found, even though they are clearly on the -L path? . It seems that my libraries and my object file have a different ELF format, which might cause the linker to not "find" the libraries.

现在，这导致了一些问题：

Now, this leads to a couple of questions:

1. 似乎我的编译器通常会生成SYSV ELF文件。 （已通过文件检查）。但是，对于该特定C ++源，它将生成Linux / GNU ELF对象文件。我不知道为什么，所以我将该源简化为一个空的main方法-突然我得到了SYSV目标文件。 C ++源文件中的哪些内容会导致编译器切换ELF格式？

1. It seems that my compiler normally generates SYSV ELF files. (Checked with file). However, for that particular C++ source, it generates a Linux/GNU ELF object file. I wonder why, so I reduced that source to an empty main method - and suddenly I get a SYSV object file. What inside a C++ source file can cause the compiler to switch the ELF format?

这是对还是错？我不能将Linux / GNU与SYSV ELF链接在一起？

是否可以选择强制编译器创建某个ELF？格式？

我正在使用Cray g ++（GCC）5.3.020151204。

I'm working with a Cray g++ (GCC) 5.3.0 20151204.

推荐答案

关于问题1：答案之一似乎是 STT_GNU_IFUNC 将导致编译器/链接器将相应目标文件的 ELF 文件格式从 SYSV 切换为 GNU / Linux 。

Regarding question 1: one of the answer seems to be that functions of type STT_GNU_IFUNC will cause the compiler/linker to switch the ELF file format of the corresponding object file from SYSV to GNU/Linux.

但是，我仍然找不到在对象文件中如何识别函数的方法。的类型为 STT_GNU_IFUNC 。查看具有 objdump ， readelf GNU / Linux 的目标文件c>和 nm 仍然没有显示类型为 STT_GNU_IFUNC 的单个函数。

However, I still couldn't find out how I can identify functions in an object file which have type STT_GNU_IFUNC. Looking at object files which are GNU/Linux with objdump, readelf and nm still don't show a single function of type STT_GNU_IFUNC.

有关 STT_GNU_IFUNC 的更多信息，请访问 https://www.airs.com/blog/archives/403 以及以下相关问题：

Some more information on STT_GNU_IFUNC can be found at https://www.airs.com/blog/archives/403 and in the following related question: How do I compile on linux to share with all distributions?

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