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<h1 id="hw-syscall">hw-syscall</h1>
<h2 id="part1">part1</h2>
<h2 id="part2">part2</h2>
<h2 id="syscall调用的过程">syscall调用的过程</h2>
<p>​ 在用户层面涉及文件有<code>usys.s</code>, <code>user.h</code>。我们发现在用户态调用的时候，我们的函数调用是带有参数的，但是陷入到系统调用中，函数中是不带有参数的。</p>
<p>举例：</p>
<pre><code>int date(struct rtcdate *); user.h
int sys_date(void); sysproc.c
</code></pre><p>​ 因此，我很好奇syscall是怎么调用的。</p>
<p><img src="syscall.png" alt=""></p>
<p>​ 最后仔细的阅读源代码，发现系统调用中虽然不带有参数，但是由于函数调用的结构化，我们在系统调用的时候可以从内存中主动去读取相关的变量值，从而能够顺利的执行相关的函数功能。不带有参数是为了系统调用时结构的统一性。</p>
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