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@@ -6,7 +6,7 @@ vsyscalls and vDSO
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This is the third part of the [chapter](http://0xax.gitbooks.io/linux-insides/content/SysCall/index.html) that describes system calls in the Linux kernel and we saw preparations after a system call caused by an userspace application and process of handling of a system call in the previous [part](http://0xax.gitbooks.io/linux-insides/content/SysCall/syscall-2.html). In this part we will look at two concepts that are very close to the system call concept, they are called `vsyscall` and `vdso`.
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-We already know what is it a `system call`. This is special routine in the Linux kernel which userspace application asks to do privileged task, like to read or to write to a file, to open a socket and etc. As you maybe know, invoking of a system call is expensive operation in the Linux kernel, because processor must interrupt currently executing task and switch context to the kernel mode and to jump again into userspace after a system call handler will finish its work. These two mechanisms - `vsyacall` and `vdso` designed to speed up this process for the certain system calls and in this part we will try to understand how these mechanisms are arranged.
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+We already know what is it a `system call`. This is special routine in the Linux kernel which userspace application asks to do privileged task, like to read or to write to a file, to open a socket and etc. As you maybe know, invoking of a system call is expensive operation in the Linux kernel, because processor must interrupt currently executing task and switch context to the kernel mode and to jump again into userspace after a system call handler will finish its work. These two mechanisms - `vsyscall` and `vdso` designed to speed up this process for the certain system calls and in this part we will try to understand how these mechanisms are arranged.
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Introduction to vsyscalls
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zhanxw