Only systems fully compliant with and certified according to the Single UNIX Specification are qualified to use the trademark; others may be called "Unix system-like" or " Unix-like " though the Open Group disapproves of this term. However, the term "Unix" is often used informally to denote any operating system that closely resembles the trademarked system. Overview Unix operating systems are widely used in both serversworkstationsand mobile devices . The Unix environment and the client—server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers.
For the special instruction step, we see syscall is also used since it is the preferred method on x64 for making syscalls. For the final step of checking the return, the code is slightly different because NTSTATUS failures are negative values whereas Linux failure codes fall into a specific range.
This part is pretty much identical to Linux with some small exceptions around the ABI related to which user mode registers are saved and which registers are passed to NtQueryDirectoryFile.
Since NT syscalls follow the x64 calling convention, the kernel does not need to save off volatile registers since that was handled by the compiler emitting instructions before the syscall to save off any volatile registers that needed to be preserved.
Syscall mechanics on WSL After looking at how syscalls are made on NT compared to Linux, we can see that there are only a few minor differences around the calling convention.
WSL includes kernel mode pico drivers lxss. The drivers do not contain code from the Linux kernel but are instead a clean room implementation of Linux-compatible kernel interfaces.
Following the original getdents example, when the syscall instruction is made the NT kernel detects that the request came from a pico process by checking state in the process structure. Since the NT kernel does not know how to handle syscalls from pico processes it saves off the register state and forwards the request to the pico driver.
The pico driver determines which Linux syscall is being invoked by inspecting the rax register and passes the parameters using the registers defined by the Linux syscall calling convention.
WSL syscall examples Where possible, lxss. Where there is no reasonable mapping lxss. Linux pipes are a good example of this case since NT also has support for pipes.
Instead, WSL implements Linux pipes directly but still uses NT functionality for primitives like synchronization and data structures. As a final example, the Linux fork syscall has no documented equivalent for Windows.
When a fork syscall is made on WSL, lxss. It then calls internal NT APIs to create the process with the correct semantics and create a thread in the process with an identical register context. Finally, it does some additional work to complete copying the process and resumes the new process so it can begin executing.
Conclusion WSL handles Linux syscalls by coordinating between the NT kernel and a pico driver which contains a clean room implementation of the Linux syscall interface. As of this article, lxss. This support will continue to improve over time especially with the great feedback we get from the community.Jun 08, · Even if the Linux kernel and Windows NT kernel had the same ABI, they expose different syscalls that do not always map one to one.
For example, the Linux kernel includes things like fork, open, and kill while the Windows NT kernel has the comparable NtCreateProcess, NtOpenFile, and NtTerminateProcess. Windows NT operating system same as MS DOS OR Windows 95 operating system software but this type of operating software is used in networking system.
Microsoft Corporation launched this operating software only to use for data transmission from one computer to another computer or networking system.
Aug 08, · Microsoft's Windows operating system is available for a variety of devices, including home and business desktop and laptop computers, smartphones, and high-powered servers. systems for personal computers include Microsoft Windows, Mac OS (and Darwin), Unix, and Linux.
2 History of Operating Systems An operating system (OS) is a software program that manages the hardware and software Microsoft's response to this change was the development of Windows NT. comparison of three operating systems, all of which run on the same PC hardware, Microsoft Windows for Workgroups is a ver- sion of Windows with integrated networking support.
Solaris is a UNIX operating system (see UNIX rosetta stone) and Linux was modeled after UNIX paradigms. But I fail to see how Windows in any incarnation is a Quasi-UNIX But I fail to see how.