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Update linux-bootstrap-4.md

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@ -336,9 +336,7 @@ ENTRY(startup_32)
#define __HEAD .section ".head.text","ax" #define __HEAD .section ".head.text","ax"
``` ```
Here, `.head.text` is the name of the section and `ax` is a set of flags. In our case, these flags show us that this section is [executable](https://en.wikipedia.org/wiki/Executable Here, `.head.text` is the name of the section and `ax` is a set of flags. In our case, these flags show us that this section is [executable](https://en.wikipedia.org/wiki/Executable). In simple terms, this means that a Linux kernel with this option set can be booted from different addresses. Technically, this is done by compiling the decompressor as [position independent code](https://en.wikipedia.org/wiki/Position-independent_code). If we look at [arch/x86/boot/compressed/Makefile](https://github.com/torvalds/linux/blob/v4.16/arch/x86/boot/compressed/Makefile), we can see that the decompressor is indeed compiled with the `-fPIC` flag:
In simple terms, this means that a Linux kernel with this option set can be booted from different addresses. Technically, this is done by compiling the decompressor as [position independent code](https://en.wikipedia.org/wiki/Position-independent_code). If we look at [arch/x86/boot/compressed/Makefile](https://github.com/torvalds/linux/blob/v4.16/arch/x86/boot/compressed/Makefile), we can see that the decompressor is indeed compiled with the `-fPIC` flag:
```Makefile ```Makefile
KBUILD_CFLAGS += -fno-strict-aliasing -fPIC KBUILD_CFLAGS += -fno-strict-aliasing -fPIC