linux 内核中的 b/w __raw_readl/__raw_writel 和 readl/writel 有什么区别？
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What's the difference b/w __raw_readl/__raw_writel and readl/writel in linux kernel?
提问by Yifan Zhang
What's the difference b/w __raw_readl/__raw_writeland readl/writelin linux kernel? It is said readl/writelis safer than __raw_readl/__raw_writel, then why do we still use __raw_readl/__raw_writel?
b/w__raw_readl/__raw_writel和readl/writellinux 内核有什么区别？都说readl/writel比安全__raw_readl/__raw_writel，那为什么还要用__raw_readl/__raw_writel呢？
Under what circumstances should we use this: __raw_readl/__raw_writelor readl/writel?
在什么情况下我们应该使用 this:__raw_readl/__raw_writel或readl/writel?
采纳答案by blueshift
It seemsto be the case that
这似乎到的情况是，
- raw denotes native byte ordering, non-raw means little-endian
- the __ prefix alternatives don't include memory barriers
- raw 表示本机字节顺序，非原始表示小端
- __ 前缀替代方案不包括内存屏障
See this LKML discussionand also the comments in linux/arch/arm/include/asm/io.h
