Problem

try 运行这个代码

if (!dlopen("../lib/libMy.so", RTLD_NOW)) {
    std::cout << dlerror() << std::endl;
    return 1;
}

导致了TLS(线程本地存储)错误:

无法在静态TLS块中分配内存

Solution

转储线程本地存储部分.tbss(静态和非静态非初始化线程本地变量)显示Tls_ErrorStruct大小为600字节(0x258)，Tls_tv大小为1600字节(0x640)，总计为2200个TLS字节:

$ objdump -C -t ../lib/libMy.so | grep -F '.tbss'

00000000000008e8 l       .tbss  0000000000000008              runtime.tlsg
0000000000000010 l       .tbss  0000000000000001              __tls_guard
0000000000000688 l       .tbss  0000000000000001              __tls_guard
...
0000000000000690 g       .tbss  0000000000000258              Tls_ErrorStruct
...
0000000000000018 g       .tbss  0000000000000640              Tls_tv

为了修复块错误，这thread_local个变量被减少到约600字节.第dlopen章成功了

Note

判断需要多少线程本地存储(TLS)0x0008f0

$ readelf -Wl ../lib/libMy.so

Elf file type is DYN (Shared object file)
Entry point 0x0
There are 10 program headers, starting at offset 64

Program Headers:
  Type           Offset    VirtAddr           PhysAddr           FileSiz  MemSiz   Flg Align
  LOAD           0x000000  0x0000000000000000 0x0000000000000000 0x48ada8 0x48ada8 R   0x1000
  LOAD           0x48b000  0x000000000048b000 0x000000000048b000 0xdab271 0xdab271 R E 0x1000
  LOAD           0x1237000 0x0000000001237000 0x0000000001237000 0x2c0564 0x2c0564 R   0x1000
  LOAD           0x14f76a0 0x00000000014f86a0 0x00000000014f86a0 0xd16172 0xd6ec50 RW  0x1000
  DYNAMIC        0x20b58c0 0x00000000020b68c0 0x00000000020b68c0 0x000220 0x000220 RW  0x8
  NOTE           0x000270  0x0000000000000270 0x0000000000000270 0x000088 0x000088 R   0x4
  TLS            0x14f76a0 0x00000000014f86a0 0x00000000014f86a0 0x000001 0x0008f0 R   0x8
  GNU_EH_FRAME   0x13fa440 0x00000000013fa440 0x00000000013fa440 0x02358c 0x02358c R   0x4
  GNU_STACK      0x000000  0x0000000000000000 0x0000000000000000 0x000000 0x000000 RW  0x10
  GNU_RELRO      0x14f76a0 0x00000000014f86a0 0x00000000014f86a0 0xbc3960 0xbc3960 R   0x1

Source

Question

我不知道如何找到动态加载器线程本地存储块大小，但确实找到了一个可能的引用here:

/* Size of the static TLS block.  Giving this initialized value
   preallocates some surplus bytes in the static TLS area.  */
size_t _dl_tls_static_size = 2048;

有没有一个linux工具或一些C++方法来确定最大线程本地存储块大小？