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Merge pull request #507 from diekmann/patch-1

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Clarify: vDSO is linked automatically with glibc
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0xAX 2017-09-02 23:56:03 +06:00 committed by GitHub
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SysCall/syscall-3.md
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@ -230,7 +230,7 @@ That's all. Now let's look on the modern concept - `vDSO`.
Introduction to vDSO
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As I already wrote above, `vsyscall` is an obsolete concept and replaced by the `vDSO` or `virtual dynamic shared object`. The main difference between the `vsyscall` and `vDSO` mechanisms is that `vDSO` maps memory pages into each process in a shared object [form](https://en.wikipedia.org/wiki/Library_%28computing%29#Shared_libraries), but `vsyscall` is static in memory and has the same address every time. For the `x86_64` architecture it is called -`linux-vdso.so.1`. All userspace applications linked with this shared library via the `glibc`. For example:
As I already wrote above, `vsyscall` is an obsolete concept and replaced by the `vDSO` or `virtual dynamic shared object`. The main difference between the `vsyscall` and `vDSO` mechanisms is that `vDSO` maps memory pages into each process in a shared object [form](https://en.wikipedia.org/wiki/Library_%28computing%29#Shared_libraries), but `vsyscall` is static in memory and has the same address every time. For the `x86_64` architecture it is called -`linux-vdso.so.1`. All userspace applications that dynamically link to `glibc` will use the `vDSO` automatically. For example:
```
~$ ldd /bin/uname