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Merge pull request #808 from renaudgermain/copyedit-booting

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copyedit: booting chapter
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Booting/linux-bootstrap-6.md
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@ -46,7 +46,7 @@ This function takes five parameters:
* `input`;
* `input_size`;
* `output`;
* `output_isze`;
* `output_size`;
* `virt_addr`.
Let's try to understand what these parameters are. The first parameter, `input` is just the `input_data` parameter of the `extract_kernel` function from the [arch/x86/boot/compressed/misc.c](https://github.com/torvalds/linux/blob/v4.16/arch/x86/boot/compressed/misc.c) source code file, cast to `unsigned long`:
@ -146,7 +146,7 @@ Now, we call another function:
initialize_identity_maps();
```
The `initialize_identity_maps` function is defined in the [arch/x86/boot/compressed/kaslr_64.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/compressed/kaslr_64.c) source code file. This function starts by initialising an instance of the `x86_mapping_info` structure called `mapping_info`:
The `initialize_identity_maps` function is defined in the [arch/x86/boot/compressed/kaslr_64.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/compressed/kaslr_64.c) source code file. This function starts by initializing an instance of the `x86_mapping_info` structure called `mapping_info`:
```C
mapping_info.alloc_pgt_page = alloc_pgt_page;
@ -254,7 +254,7 @@ add_identity_map(mem_avoid[MEM_AVOID_ZO_RANGE].start,
mem_avoid[MEM_AVOID_ZO_RANGE].size);
```
THe `mem_avoid_init` function first tries to avoid memory regions currently used to decompress the kernel. We fill an entry from the `mem_avoid` array with the start address and the size of the relevant region and call the `add_identity_map` function, which builds the identity mapped pages for this region. The `add_identity_map` function is defined in the [arch/x86/boot/compressed/kaslr_64.c](https://github.com/torvalds/linux/blob/v4.16/arch/x86/boot/compressed/kaslr_64.c) source code file and looks like this:
The `mem_avoid_init` function first tries to avoid memory regions currently used to decompress the kernel. We fill an entry from the `mem_avoid` array with the start address and the size of the relevant region and call the `add_identity_map` function, which builds the identity mapped pages for this region. The `add_identity_map` function is defined in the [arch/x86/boot/compressed/kaslr_64.c](https://github.com/torvalds/linux/blob/v4.16/arch/x86/boot/compressed/kaslr_64.c) source code file and looks like this:
```C
void add_identity_map(unsigned long start, unsigned long size)