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"description" : "Description Modern microcontrollers nowadays support at least two privilege levels. Intel\/AMD x86-64 family supports 4 levels, whilst ARM (32bit) microcontrollers support up to 7 levels (6 privileged, 1 non-privileged).\nModern operating systems support at least 2 levels:\nUser space: For applications to run in unprivileged user mode Kernel space: For the kernel (and all its components) to run in privileged mode – kernel mode Address of these 2 spaces are separate.",
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<meta property="og:description" content="Description Modern microcontrollers nowadays support at least two privilege levels. Intel/AMD x86-64 family supports 4 levels, whilst ARM (32bit) microcontrollers support up to 7 levels (6 privileged, 1 non-privileged).
Modern operating systems support at least 2 levels:
User space: For applications to run in unprivileged user mode Kernel space: For the kernel (and all its components) to run in privileged mode – kernel mode Address of these 2 spaces are separate." />
<meta name="description" content="Description Modern microcontrollers nowadays support at least two privilege levels. Intel/AMD x86-64 family supports 4 levels, whilst ARM (32bit) microcontrollers support up to 7 levels (6 privileged, 1 non-privileged).
Modern operating systems support at least 2 levels:
User space: For applications to run in unprivileged user mode Kernel space: For the kernel (and all its components) to run in privileged mode – kernel mode Address of these 2 spaces are separate." />
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<h1 class="post-title">Architecture of Linux Kernel</h1>
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<time class="post-date" datetime="2022-09-03 14:33:37 CST">
03 Sep 2022
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<a target="_blank" href="https://garhve.com">@garhve</a>
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<p>Modern microcontrollers nowadays support at least two privilege levels. Intel/AMD x86-64 family supports 4 levels, whilst ARM (32bit) microcontrollers support up to 7 levels (6 privileged, 1 non-privileged).</p>
<p>Modern operating systems support at least 2 levels:</p>
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<li><strong>User space</strong>: For applications to run in unprivileged user mode</li>
<li><strong>Kernel space</strong>: For the kernel (and all its components) to run in privileged mode – kernel mode</li>
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<p>Address of these 2 spaces are separate.</p>
<p>Applications in user mode will auto-linked to glibc(the GNU standard C library). Libraries only available in user mode, kernel mode doesn’t have this conception. An application only can through <strong>System call</strong> to access kernel. On the other hand, system calls are the only legal entry point into the kernel space.</p>
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<p>Libraries APIs: man section 3
System calls APIs: man section 2</p>
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<p>to be continue…</p>
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