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Apple Computing Products:
macOS - Desktop Hardware
G4 very slow, sometimes shuts down
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<blockquote data-quote="Mac SK" data-source="post: 907341" data-attributes="member: 21908"><p>To understand this question, you need to understand the concepts of User mode and system/privileged mode of operation. In an operating system, there are (generally) two modes of operation: user mode and system mode. User mode is where all the user (program) code is executed. System mode is where the kernel/operating system code is executed. When a user program requests a service from the operating system via a system call, a switch happens from the user mode to kernel/system mode.</p><p></p><p>For any program to run (user or kernel), a program stack is essential for all stack based computer architectures. The stack is where local variables are stored, function call stack frames are created, etc So, when in user mode, a user program has a stack. But, when the kernel code starts executing, it needs its own kernel stack.</p></blockquote><p></p>
[QUOTE="Mac SK, post: 907341, member: 21908"] To understand this question, you need to understand the concepts of User mode and system/privileged mode of operation. In an operating system, there are (generally) two modes of operation: user mode and system mode. User mode is where all the user (program) code is executed. System mode is where the kernel/operating system code is executed. When a user program requests a service from the operating system via a system call, a switch happens from the user mode to kernel/system mode. For any program to run (user or kernel), a program stack is essential for all stack based computer architectures. The stack is where local variables are stored, function call stack frames are created, etc So, when in user mode, a user program has a stack. But, when the kernel code starts executing, it needs its own kernel stack. [/QUOTE]
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Apple Computing Products:
macOS - Desktop Hardware
G4 very slow, sometimes shuts down
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