为什么在单处理器上sizeof(spinlock_t)大于零? [英] Why sizeof(spinlock_t) is greater than zero on uni-processor?

问题描述

下面的行将输出打印为4，而我期望为0.

The following line printed output as 4 whereas I was expecting 0.

 printk(KERN_INFO "size of spinlock_t  %d\n", sizeof(spinlock_t));

我在具有单个cpu的系统上尝试过此操作.在构建像CONFIG_DEBUG_SPINLOCK or CONFIG_DEBUG_LOCK_ALLOC这样的内核时，未启用任何调试标志.根据内核头文件，它应该为零，但输出与此不一致，有任何猜测吗?

I tried this on a system with single cpu. No debugging flags are enabled while building kernel like CONFIG_DEBUG_SPINLOCK or CONFIG_DEBUG_LOCK_ALLOC. According to kernel header files, it should be zero but output is not consistent with it, any guesses ?

推荐答案

我最好的猜测是，尽管您只有一个CPU，但是内核仍然使用CONFIG_SMP设置进行编译.

The best guess I have is that although you have a single CPU, the kernel is still compiled with CONFIG_SMP set.

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