I am getting a segfault when accessing shared memory (memory mapped file, using a fixed address of 0x60000000 ) from within a share object (.so).
当从共享对象（.so）中访问共享内存（内存映射文件，使用固定地址0x60000000）时，我得到一个段错误。
We have many applications accessing this shared memory without difficulty. My app is different in that I create a small .so with it and the .so is the one calling mmap and accessing the shared memory.
我们有很多应用程序毫无困难地访问此共享内存。我的应用程序不同之处在于我用它创建一个小的.so而.so是调用mmap并访问共享内存的.so。
The mmap() returns just fine. My requested address is returned back properly. But as soon as I try to access the memory from within this .so, it seg faults.
mmap（）返回正常。我要求的地址已正确退回。但是一旦我尝试从这个.so中访问内存，就会出现故障。
I can't figure out what is unique about a .so that would prevent it from accessing shared memory this way.
我无法弄清楚.so的独特之处在于它会阻止它以这种方式访问共享内存。
Anyone have thoughts?
有人有想法吗？
1 个解决方案
#1
2
In general, accessing mmaped memory from a shared library is in no way different from accessing it from a main executable, and you are likely barking up the wrong tree. That said, this:
通常，从共享库访问mmaped内存与从主可执行文件访问mmaped内存完全不同，并且你可能正在咆哮错误的树。那说，这个：
memory mapped file, using a fixed address of
0x60000000内存映射文件，使用固定地址0x60000000
is generally a very bad idea, because you have no control over what (if anything) was mmaped there before. A MAP_FIXED mapping will simply remove any previous mapping that existed. If your library itself happens to be mapped there, then you'll replace the library .text, or .data, and the result is almost certain to be a mysterious crash.
通常是一个非常糟糕的主意，因为你无法控制以前曾在那里做过什么（如果有的话）。 MAP_FIXED映射将简单地删除任何先前存在的映射。如果您的库本身恰好映射到那里，那么您将替换库.text或.data，结果几乎肯定是一个神秘的崩溃。
#1
2
In general, accessing mmaped memory from a shared library is in no way different from accessing it from a main executable, and you are likely barking up the wrong tree. That said, this:
通常，从共享库访问mmaped内存与从主可执行文件访问mmaped内存完全不同，并且你可能正在咆哮错误的树。那说，这个：
memory mapped file, using a fixed address of
0x60000000内存映射文件，使用固定地址0x60000000
is generally a very bad idea, because you have no control over what (if anything) was mmaped there before. A MAP_FIXED mapping will simply remove any previous mapping that existed. If your library itself happens to be mapped there, then you'll replace the library .text, or .data, and the result is almost certain to be a mysterious crash.
通常是一个非常糟糕的主意，因为你无法控制以前曾在那里做过什么（如果有的话）。 MAP_FIXED映射将简单地删除任何先前存在的映射。如果您的库本身恰好映射到那里，那么您将替换库.text或.data，结果几乎肯定是一个神秘的崩溃。